I get this same thing. I've tried restarting with no success. There appears to be an error in the installation. I originally was updating a prior (working) install of VirtualBox 4.3.2. When the VB 4.3.12 install failed, I ran the VB uninstall tool since my prior (working) VB install was no completely wiped out.
Since then, I've tried restarting the Mac with no difference. Also an attempt to install VB 4.3.10 also ends in this same error.
Install image - VirtualBox-4.3.12-93733-OSX.dmg
Mac - OSX 10.9.3
kernel - Darwin skini.local 13.2.0 Darwin Kernel Version 13.2.0: Thu Apr 17 23:03:13 PDT 2014; root:xnu-2422.100.13~1/RELEASE_X86_64 x86_64
May 30 10:35:05 skini.local Installer[390]: LSExceptions [0x7fdf82506530] loaded
May 30 10:35:05 skini.local Installer[390]: @(#)PROGRAM:Install PROJECT:Install-846
May 30 10:35:05 skini.local Installer[390]: @(#)PROGRAM:Installer PROJECT:Installer-721
May 30 10:35:05 skini.local Installer[390]: Hardware: Macmini5,2 @ 2.70 GHz (x 4), 8192 MB RAM
May 30 10:35:05 skini.local Installer[390]: Running OS Build: Mac OS X 10.9.3 (13D65)
May 30 10:35:05 skini.local Installer[390]: Env: PATH=/usr/bin:/bin:/usr/sbin:/sbin
May 30 10:35:05 skini.local Installer[390]: Env: TMPDIR=/var/folders/0k/zfpvbg756lvcmtq9j5rdb59h0000gn/T/
May 30 10:35:05 skini.local Installer[390]: Env: SHELL=/bin/bash
May 30 10:35:05 skini.local Installer[390]: Env: HOME=/Users/nada
May 30 10:35:05 skini.local Installer[390]: Env: USER=nada
May 30 10:35:05 skini.local Installer[390]: Env: LOGNAME=nada
May 30 10:35:05 skini.local Installer[390]: Env: SSH_AUTH_SOCK=/tmp/launch-SQzUPS/Listeners
May 30 10:35:05 skini.local Installer[390]: Env: Apple_PubSub_Socket_Render=/tmp/launch-RTwtvM/Render
May 30 10:35:05 skini.local Installer[390]: Env: DISPLAY=/tmp/launch-jos4Hs/org.macosforge.xquartz:0
May 30 10:35:05 skini.local Installer[390]: Env: COMMAND_MODE=unix2003
May 30 10:35:05 skini.local Installer[390]: Env: __CHECKFIX1436934=1
May 30 10:35:05 skini.local Installer[390]: Env: __CF_USER_TEXT_ENCODING=0x1F5:0:0
May 30 10:35:05 skini.local Installer[390]: Oracle VM VirtualBox 4.3.12 Installation Log
May 30 10:35:05 skini.local Installer[390]: Opened from: /Volumes/VirtualBox/VirtualBox.pkg
May 30 10:35:05 skini.local Installer[390]: Product archive /Volumes/VirtualBox/VirtualBox.pkg trustLevel=202
May 30 10:35:07 skini.local Installer[390]: JS: Hardware architecture detected: x86_64
May 30 10:35:07 skini.local Installer[390]: JS: OS version detected: 10.9.3
May 30 10:35:07 skini.local Installer[390]: JS: system.run /bin/sh .. returned: 1 result=true
May 30 10:35:07 skini.local Installer[390]: JS: result:true
May 30 10:35:09 skini.local Installer[390]: InstallerStatusNotifications plugin loaded
May 30 10:35:14 skini.local runner[404]: Administrator authorization granted.
May 30 10:35:14 skini.local Installer[390]: ================================================================================
May 30 10:35:14 skini.local Installer[390]: User picked Standard Install
May 30 10:35:14 skini.local Installer[390]: Choices selected for installation:
May 30 10:35:14 skini.local Installer[390]: Upgrade: "Oracle VM VirtualBox"
May 30 10:35:14 skini.local Installer[390]: Upgrade: "Oracle VM VirtualBox Kernel Extensions"
May 30 10:35:14 skini.local Installer[390]: VirtualBox.pkg#VBoxKEXTs.pkg : org.virtualbox.pkg.vboxkexts : 4.3.12
May 30 10:35:14 skini.local Installer[390]: Upgrade: "Oracle VM VirtualBox"
May 30 10:35:14 skini.local Installer[390]: VirtualBox.pkg#VirtualBox.pkg : org.virtualbox.pkg.virtualbox : 4.3.12
May 30 10:35:14 skini.local Installer[390]: Upgrade: "Oracle VM VirtualBox Command Line Utilities"
May 30 10:35:14 skini.local Installer[390]: VirtualBox.pkg#VirtualBoxCLI.pkg : org.virtualbox.pkg.virtualboxcli : 4.3.12
May 30 10:35:14 skini.local Installer[390]: ================================================================================
May 30 10:35:14 skini.local Installer[390]: It took 0.00 seconds to summarize the package selections.
May 30 10:35:14 skini.local Installer[390]: -[IFDInstallController(Private) _buildInstallPlan]: location = file://localhost
May 30 10:35:14 skini.local Installer[390]: -[IFDInstallController(Private) _buildInstallPlan]: file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VBoxKEXTs.pkg
May 30 10:35:14 skini.local Installer[390]: -[IFDInstallController(Private) _buildInstallPlan]: file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VirtualBox.pkg
May 30 10:35:14 skini.local Installer[390]: -[IFDInstallController(Private) _buildInstallPlan]: file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VirtualBoxCLI.pkg
May 30 10:35:14 skini.local Installer[390]: Set authorization level to root for session
May 30 10:35:14 skini.local Installer[390]: Will use PK session
May 30 10:35:14 skini.local Installer[390]: Starting installation:
May 30 10:35:14 skini.local Installer[390]: Configuring volume "Macintosh HD"
May 30 10:35:14 skini.local Installer[390]: Preparing disk for local booted install.
May 30 10:35:14 skini.local Installer[390]: Free space on "Macintosh HD": 128.82 GB (128816939008 bytes).
May 30 10:35:14 skini.local Installer[390]: Create temporary directory "/var/folders/0k/zfpvbg756lvcmtq9j5rdb59h0000gn/T//Install.390LUhcOI"
May 30 10:35:14 skini.local Installer[390]: IFPKInstallElement (3 packages)
May 30 10:35:14 skini.local Installer[390]: Using authorization level of root for IFPKInstallElement
May 30 10:35:14 skini.local installd[409]: installd: Starting
May 30 10:35:14 skini.local installd[409]: installd: uid=0, euid=0
May 30 10:35:14 skini.local installd[409]: PackageKit: Adding client PKInstallDaemonClient pid=390, uid=501 (/System/Library/CoreServices/Installer.app/Contents/MacOS/Installer)
May 30 10:35:14 skini.local Installer[390]: PackageKit: Enqueuing install with boosting
May 30 10:35:14 skini.local installd[409]: PackageKit: ----- Begin install -----
May 30 10:35:14 skini.local installd[409]: PackageKit: request=PKInstallRequest <3 packages, destination=/>
May 30 10:35:14 skini.local installd[409]: PackageKit: packages=(
"PKLeopardPackage <file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VBoxKEXTs.pkg>",
"PKLeopardPackage <file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VirtualBox.pkg>",
"PKLeopardPackage <file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VirtualBoxCLI.pkg>"
)
May 30 10:35:15 skini.local installd[409]: PackageKit: Will do receipt-based obsoleting for package identifier org.virtualbox.pkg.virtualboxcli (prefix path=usr/bin)
May 30 10:35:15 skini.local installd[409]: PackageKit: Extracting file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VBoxKEXTs.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/06CCAC17-2B52-4E93-8265-939DC55BF336.activeSandbox/Root/Library/Application Support/VirtualBox, uid=0)
May 30 10:35:17 skini.local Installer[390]: LSExceptions [0x7fdf82506530] unloaded
May 30 10:35:23 skini.local installd[409]: PackageKit: Extracting file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VirtualBox.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/06CCAC17-2B52-4E93-8265-939DC55BF336.activeSandbox/Root/Applications, uid=0)
May 30 10:35:24 skini.local installd[409]: PackageKit: Extracting file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VirtualBoxCLI.pkg (destination=/var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/06CCAC17-2B52-4E93-8265-939DC55BF336.activeSandbox/Root/usr/bin, uid=0)
May 30 10:35:24 skini.local installd[409]: PackageKit: prevent user idle system sleep
May 30 10:35:24 skini.local installd[409]: PackageKit: suspending backupd
May 30 10:35:25 skini.local installd[409]: PackageKit: Executing script "./preflight" in /private/tmp/PKInstallSandbox.V5ycuO/Scripts/org.virtualbox.pkg.virtualbox.Hzs8de
May 30 10:35:25 skini.local install_monitor[411]: Temporarily excluding: /Applications, /Library, /System, /bin, /private, /sbin, /usr
May 30 10:35:25 skini.local installd[409]: PackageKit: Using trashcan path /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/T/PKInstallSandboxTrash/06CCAC17-2B52-4E93-8265-939DC55BF336.sandboxTrash for sandbox /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/06CCAC17-2B52-4E93-8265-939DC55BF336.activeSandbox
May 30 10:35:25 skini.local installd[409]: PackageKit: Shoving /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/06CCAC17-2B52-4E93-8265-939DC55BF336.activeSandbox/Root (3 items) to /
May 30 10:35:25 skini.local installd[409]: PackageKit: Executing script "./postflight" in /private/tmp/PKInstallSandbox.V5ycuO/Scripts/org.virtualbox.pkg.vboxkexts.hOGQBk
May 30 10:35:25 skini.local installd[409]: ./postflight: /Library/LaunchDaemons/org.virtualbox.startup.plist
May 30 10:35:25 skini.local installd[409]: ./postflight: (kernel) Can't unload kext org.virtualbox.kext.VBoxUSB; classes have instances:
May 30 10:35:25 skini.local installd[409]: ./postflight: (kernel) Kext org.virtualbox.kext.VBoxUSB class org_virtualbox_VBoxUSB has 1 instance.
May 30 10:35:25 skini.local installd[409]: ./postflight: Failed to unload org.virtualbox.kext.VBoxUSB - (libkern/kext) kext is in use or retained (cannot unload).
May 30 10:35:25 skini.local installd[409]: ./postflight: (kernel) Can't remove kext org.virtualbox.kext.VBoxDrv; services failed to terminate - 0xdc008018.
May 30 10:35:25 skini.local installd[409]: ./postflight: Failed to unload org.virtualbox.kext.VBoxDrv - (libkern/kext) kext is in use or retained (cannot unload).
May 30 10:35:25 skini.local installd[409]: ./postflight: /Library/Application Support/VirtualBox/VBoxDrv.kext failed to load - (libkern/kext) different version/uuid already loaded; check the system/kernel logs for errors or try kextutil(8).
May 30 10:35:25 skini.local install_monitor[411]: Re-included: /Applications, /Library, /System, /bin, /private, /sbin, /usr
May 30 10:35:25 skini.local installd[409]: PackageKit: releasing backupd
May 30 10:35:25 skini.local installd[409]: PackageKit: allow user idle system sleep
May 30 10:35:25 skini.local installd[409]: PackageKit: Install Failed: Error Domain=PKInstallErrorDomain Code=112 "An error occurred while running scripts from the package “VirtualBox.pkg”." UserInfo=0x7faea0c42830 {NSFilePath=./postflight, NSURL=file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VBoxKEXTs.pkg, PKInstallPackageIdentifier=org.virtualbox.pkg.vboxkexts, NSLocalizedDescription=An error occurred while running scripts from the package “VirtualBox.pkg”.} {
NSFilePath = "./postflight";
NSLocalizedDescription = "An error occurred while running scripts from the package \U201cVirtualBox.pkg\U201d.";
NSURL = "file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VBoxKEXTs.pkg";
PKInstallPackageIdentifier = "org.virtualbox.pkg.vboxkexts";
}
May 30 10:35:25 skini.local Installer[390]: install:didFailWithError:Error Domain=PKInstallErrorDomain Code=112 "An error occurred while running scripts from the package “VirtualBox.pkg”." UserInfo=0x7fdf84a76540 {NSFilePath=./postflight, NSURL=file://localhost/Volumes/VirtualBox/VirtualBox.pkg#VBoxKEXTs.pkg, PKInstallPackageIdentifier=org.virtualbox.pkg.vboxkexts, NSLocalizedDescription=An error occurred while running scripts from the package “VirtualBox.pkg”.}
May 30 10:35:25 skini.local installd[409]: PackageKit: Running idle tasks
May 30 10:35:25 skini.local installd[409]: PackageKit: Removing client PKInstallDaemonClient pid=390, uid=501 (/System/Library/CoreServices/Installer.app/Contents/MacOS/Installer)
May 30 10:35:25 skini.local installd[409]: PackageKit: Done with sandbox removals
May 30 10:35:26 skini.local installd[409]: PackageKit: Sandbox /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/088BB381-65D3-469E-BC76-371ACAB7C1A0.sandbox: relevance 169
May 30 10:35:26 skini.local installd[409]: PackageKit: Sandbox /var/folders/zz/zyxvpxvq6csfxvn_n0000000000000/C/PKInstallSandboxManager/7C773FCF-B390-4F9B-84E2-4EC2B5161B58.sandbox: relevance 436
May 30 10:35:26 skini.local Installer[390]: Install failed: The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.
May 30 10:35:26 skini.local Installer[390]: IFDInstallController 8255AC60 state = 8
May 30 10:35:26 skini.local Installer[390]: Displaying 'Install Failed' UI.
May 30 10:35:26 skini.local Installer[390]: 'Install Failed' UI displayed message:'The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.'.