I've never heard of that with vista, much less any other version of windows. My guess is that it is some sort of malware/virus. Seeing that you cannot get into safe mode, your best bet may be to just restore it back to factory condition. If there is necessary data, you may want to remove the drive, put it in an external enclosure and get what you want off of it first. While your at it, you can run a virus scan as well.
I have not removed the drive and I am not sure how to restore it to factory condition.