virtualbox.org

I have a MacBook Pro running OS X Yosemite Version 10.10.2. I am using VirtualBox version 4.3.26 r98988 to run Windows 7 Ultimate version 6.1.7601 Service Pack 1 Build 7601. When I open VirtualBox, I get the following message:
One or more virtual hard disks, CD/DVD or floppy disk image files are not currently accessible. As a result, you will not be able to operate virtual machines that use these files until they become accessible later.
Press Check to open the Virtual Media Manager window and see which files are inaccessible, or press Ignore to ignore this message.

If I left click the “Check” button, the “Virtual Media Manage” dialog box opens. The “Optical disks” tab displays a yellow box with the following:
‘/Users/vjyuliano/downloads/VboxGuestAdditions.iso’
Attached to: Not Attached
__________________________________________________
Could not open the medium
‘/Users/vjyuliano/downloads/VboxGuestAdditions.iso’.
VD: error VERR_FILE_NOT_FOUND opening image file
‘/Users/vjyuliano/downloads/VboxGuestAdditions.iso’
(VERR_FILE_NOT_FOUND)

I have two USB 3.0 hard drives. They work fine with OS X Yosemite. They will not work with VirtualBox. How do I fix this?

Two separate problems.

1. You apparently downloaded the VBoxGuestAdditions.iso separately instead of using the ones that come in the VirtualBox package which is why it would be in your Downloads folder. You then attached it to your guest and either moved or deleted the file from the Downloads folder so VirtualBox can no longer find it. You need to look in the Storage settings for your guest and detach it from the CD/DVD Controller.

2. VirtualBox doesn't support USB 3.0 so to access USB 3.0 drives you would have to either use USB 2.0 cables, plug them into a USB 2.0 Hub, or select them as Shared Folders.