[snorgle] sounds like it could be a virus (My father-in-law had - I think - Bugbear, which stopped him from turning his machine off. Of course, he could just have unplugged it ... It also seemed to disable Norton anti-virus, but AVG found it in the end.) grisoft.com have a good, free anti-virus (AVG), and also utilities for extracting individual viruses once they have been identified.