...30+ infected viruses...
Virus = unstable system with strange behaviour. Getting ridd of viruses can sometimes trash files and in rare ocasions also the RDB of the HD.
As this have happened before as you say let me give you a good advice, virus check all your harddrives, your backups and your floppys and then make it a habbit of always having a virus checker running in background and check your harddrive every once in a while.
