This problem happened to me fairly recently. No one was working on it when it happened. I just came to my computer after I woke up and there were two program windows open [not fullscreen, and both windows normally open overnight. One is Ad-Aware SE Personal the other is Spyware- Search and Destroy] but no desktop behind it. No icons, no toolbar, only blue background.
I shut down the computer and rebooted. When I signed on again I realized that I couldn't get to the desktop or even see it. The only thing I could do was open Task Manager and shut down.
After a while I realized that I could choose the 'new program' option to carry out normal tasks.
It wouldn't be that bad if it wasn't an old computer basically loaned to me by my company. Plus if they urgently needed past information or more computers I would have to return it.
So because it's an office computer I can't wipe the drive an reinstall because I don't have the disks or go freely through the system deleting suspicious items. On top of that I can't just leave it unfixed in case it's needed.

If someone could tell me whats going on with my computer, or even better, tell my how I could fix it, that would be amazing.

thanks
evan