This is a rootkit behavior: a hidden virus. Thanks avast is detecting it... it could have missed and you'll be in trouble.
In the Professional version, there is an option to set 'automated' actions to be taken when a virus is found. In the Home, if the virus is recurrent, you need to act each time.
If a virus is replicating (coming and coming again), you could follow the general cleaning procedure:
1. Disable System Restore on
Windows ME or
Windows XP. System Restore cannot be disabled on Windows 9x and it's not available in Windows 2k. After boot you can enable System Restore again after step 3.
2. Clean your temporary files. You can use
CleanUp or the
Windows Advanced Care features for that.
3. Schedule a boot time scanning with avast. Start avast! > Right click the skin > Schedule a boot-time scanning. Select for scanning archives. Boot. Other option is scanning in
SafeMode (repeatedly press F8 while booting).
4. It will be good if you download, install, update and run
AVG Antispyware. Some users recommend
SUPERantispyware,
Spyware Terminator and/or
a-squared (take care about false positives).
If any infection is detected, better and safer is send the file to Quarantine than to simple delete than.
5. If you still detecting any strange behavior or even you're sure you're not clean, maybe it will be good to test your machine with
anti-rootkit applications. I suggest
AVG,
Panda and/or
F-Secure BlackLight.
6. Also, if you still detecting strange behaviors or you want to be sure you're clean, maybe making a
HijackThis log to post here and, specially, scan and submit to on-line analysis the
RunScanner log would help to identify the problem and the solution.
7. After you're clean, use the immunization of
SpywareBlaster or, which is better, the
Windows Advanced Care features of spyware/adware cleaning and removal.
8. Finally, when you're clean, check for insecure applications with
Secunia Software Inspector to update insecure applications and avoid reinfection.
