system
7
To OP…I’d try above as Igor suggests.
Since you are running XP from Command prompt >CHKDSK C: /r
http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/chkdsk.mspx?mfr=true
If you want to go the A/V Virus route here is thread on how-to post to get help: http://forum.avast.com/index.php?topic=53253.0
I have used the online scanner that dolphins recommends BUT as Para-noid has posted I would first go thru the experts on this and get their direction…they have very good set/progression on how to go after possible infections. To get their help they will expect you to go thru the above thread and post the logs.
Hope that helps.