My configuration is -- Linux (as host) using VirtualBox with 3 virtual machines -- all Windows: XP, Vista, Windows 7. All virtual disks are on the same partition, all worked fine until today.
Today XP and Vista works, but for Win7 -- VB disables the start. So it is not the case, I start virtual machine and it crashes, but I cannot even start it, because start button for it is disabled. Virtual Box shows no info why.
What's more when I try to change any settings I get obscure message saying
Failed to save the settings of the virtual machine to .
Please note the empty space before period. Maybe some configuration file was lost...
Anyway, the question is: how to diagnose such problem as this one? I.e. how to find the source of the problem?