My Virtual Box worked fine for a week and then it stopped opening up my Virtual Machine Operating Systems.
I had the following 32 bit O S’s working: Windows XP, centOS and openSUSE!
I installed Windows 7 (64 bit) and everything worked fine for a few weeks!
I downloaded the Oracle Virtualbox from the Oracle Website instead of the Ubuntu Software Center???
What worked for me was to recompile my Oracle Virtualbox kernel (I’m dealing with Oracle VM) with “sudo /etc/init.d/vboxdrv setup”. This worked!
Try this before you delete your operating systems for a new Oracle VM installation.
I don’t know how to prove what caused the problem.
I suspect it was the 64 bit Windows 7 VB Installation.
My Windows XP, centOS and openSUSE installations are all 32 bit!
With this many VB installations you can see why I didn’t want to spend the time re-installing the virtualbox and Operating Systems.