I installed Virtualbox through yast and then installed an operating system. The guest OS will start and when it begins loading all the modules, etc, it restarts my entire computer. Is there a bad configuration or is it something else I need to look at?
I can say that I also use VirtualBox. When you configure a Guest, never give it more that half of all of your memory or CPU power. On occasion, some OS’ may not want to load, but it is very unusual for it to reboot your PC. When I installed VirtualBox, I down loaded the most recent version directly from Oracle which may be a better approach than using YaST, but give us more details on your system setup first.
I would say then you need to make sure the guest OS, if its openSUSE, needs to be the final release of openSUSE 11.4 or 12.1. Since it is Windows that blows up, you need to visit the Oracle or even Windows sites to look for solutions. We help with openSUSE and running VirtualBox with openSUSE as a host, but in this case, its hard to help very much and so far you have not provided enough details to help with any openSUSE problem.