Try to uninstall AVG and boot.
Install avast and boot. Update it and registered it. If you can't go on-line, do it from other computer, copying the registration key.
After that, 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.
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).
Clean your temporary files. You can use [ur=http://www.stevengould.org/downloads/cleanup/]CleanUp[/url] or the
Windows Advanced Care features for that.
It will be good if you download, install, update and run other trojan remover tools:
a-squared and/or
Free AVG Antispyware (trojan removers). Some users recommend
SUPERantispyware or
Spyware Terminator.
Use the immunization of
SpywareBlaster or, which is better, the
Windows Advanced Care features of spyware/adware cleaning and removal.