Hi Inva,

please follow the advice in your 1st posting:
http://forum.avast.com/index.php?board=2;action=display;threadid=5171
e.g. Onlinescans and defrag & disk-Cleanup (normal boot or safeMode)

what about a full scan with avast ? does it run through without problems ?
with or without archive scanning ?

please also post a hijackthis-Logfile: http://hjt.klaffke.de/en