virus attack

I think that you didn't have a virus, especially if an antivirus program failed to find one. It sometimes (too often) happens that Windows itself gets screwed up and the best solution then is to either run the Repair utility or reformat and reinstall everything. We never know when something like this is going to happen (whether it's just a malfunction or an actual virus) which is why regular backups of data and an organised approach to keeping essential software available in case it needs re-installing is something that can't be overemphasised!

My pc was not attacked by virus for more than a year. Because I always connect internet through proxy and manually immunizeed my pen drive from viruses. My only problem are spywares so I use spyware terminator in my PC. i am using Avast AV but not updating it frequently as I have data based internet plan.