virtualbox.org

I've recently updated to VirtualBox 4.3.8 by fully removing old version (4.2), installing the new one together with the only extension pack from the official 'Downloads' page.

My processor is Intel Core Quad Q8400, OS is Windows 7 x64 Pro English (regional settings like date format are Russian, through).

When I've tried to start one of my old VMs, VirtualBox showed me black window for a second and then failed with the following error:
Then I tried to install old version, export my VM to OVF and then import it in the newer version. No luck. Then I tried to create new machine from scratch: I've selected ubuntu 32-bit, disabled all acceleration, audio, network, USB 2.0 and still no luck with the same error.

Old version (4.2) worked OK. What could go wrong?

Post a VM log file please. See Minimum information needed for assistance.

Here is VM log. Accelerations disabled, no network/audio/usb2.0, freshly created, no installation ISO was selected.

VBox.log wrote: 00:00:09.317502 VMSetError: The version of the device registration structure is unknown to this VBox version. Either mixing incompatible versions or the structure isn't correctly initialized.
00:00:09.317832 ERROR [COM]: aRC=E_FAIL (0x80004005) aIID={8ab7c520-2442-4b66-8d74-4ff1e195d2b6} aComponent={Console} aText={The version of the device registration structure is unknown to this VBox version. Either mixing incompatible versions or the structure isn't correctly initialized. (VERR_PDM_UNKNOWN_DEVREG_VERSION)}, preserve=false
00:00:09.378735 Power up failed (vrc=VERR_PDM_UNKNOWN_DEVREG_VERSION, rc=E_FAIL (0X80004005))

There doesn't seem to be anything more in the log: the error message says you've been mixing and matching VirtualBox executables, e.g. copying them to new folders and forgetting that the copies don't get updated. If you've made copies of VBoxManage or anything else in order to avoid typing in a path, then you should delete them now. You may also need to reinstall VirtualBox.

I haven't done anything like that - no copying of executables. If I need to run VBoxManage.exe, I either add to to PATH or create an alias batch file or type full path.

I have, however, mixed mingw and msys executables in the PATH (find, grep, sh, gcc, make, which may be confusing if, for example, VirtualBox expects find.exe to be the one by Microsoft). If I uninstall VirtualBox completely and remove C:\Program Files\Oracle\VirtualBox (which has leftover extension pack after uninstallation) and then install 4.3 from scratch, problem persists. If I install 4.2 (without even uninstalling 4.3), it works.

May I clean something like COM objects cache or...?

As far as I know, VirtualBox has no dependencies on the command line tools you mention.

If you didn't explicitly copy the executables then another possibility is that some time in the past (4.2.x) you installed the VBox program in an unusual location, and you added that location to a search path. Now VirtualBox is stored in standard location and that search path is causing confusion. Do you have anything VirtualBox related in a system search path?

No, I haven't installed any emulation-related software except VirtualBox, and it is always installed in its default path. List of all *.exe files available in my PATH is attached.

Actually your problem is caused by an outdated version of VirtualKD.