virtualbox.org

I´ve had quite some problems running VB on whatever host with whatever guest.
After a lot of experimenting, I narrowed down the problem to 2 details and I solved both of them.
So I´m sharing my findings here.

1) MultiCore CPU and threaded optimization.
If you have a MultiCore CPU, VB has some conflicts, especially with the graphics drivers on the host machine (not sure whether that´s a problem of VB or the graphics drivers).
If you have an NVidia graphics card and Windows OS, you can solve this in the NVidia Control Panel.
Go to "Manage 3D settings", scroll down to "Threaded Optimization" and set it to "On".
If you have some other graphics card, like ATI or Intel CPU internal (as far as I know) there is no such setting.
In this case do NOT give your guests more than 1 CPU.

2) USB settings.
Most BIOS have a setting for "USB EHCI Hand-Off" (or similar).
This is a workaround for OS without EHCI support and it´s usually enabled by default.
If your OS supports EHCI this MUST be set to disabled, else VB will have all kinds of problems, up to crashes as soon as you enable the USB controller for a guest.
If your BIOS has no setting for this, it will most likely be enabled without an option to disable it, in such case a BIOS update might add the option.
If your OS does not support EHCI and/or you can´t disable this, do NOT enable USB for your guests.

Thanks for finding this. We are already aware of issue 1), it's caused by the nVidia driver. If you install the latest version, you should not have this problem any more. It was a problem with version 275 and above until it got fixed. I don't know which version it was fixed in, as I never had this problem and run Linux as Host (so far, I've only heard reports from Windows Hosts).