AVG 8.0's LinkScanner and "security toolbar" may be the source of your
problems. (I didn't consider this as I'd never install either of them and
didn't think anyone else would either. They've been the source of
problems for many WinXP and Vista users.) Try the following (if you want
to keep using AVG):
1. Download a fresh copy of the installer, saving it to your C: drive
(i.e, C:\avg_free_stf_en_8_100a1295.exe) =>
http://www.grisoft.cz/filedir/inst/avg_free_stf_en_8_100a1295.exe
2. Uninstall AVG 8.0 via Add/Remove Programs & reboot.
NB: You're "working without a net" now: Don't to ANYTHING else online
(e.g., browsing; reading email; chatting) until you've got AVG 8.0
installed, properly configured, and updated!
3. Carefully follow these instructions to install AVG 8.0:
http://free.grisoft.com/ww.faq.num-1338
Tip: Do NOT install the toolbar (if offered) or either of the email
scanners. Email Scanning provides no additional protection, it's a major
source of corruption and problems in Outlook Express, and even Symantec
(NAV) says it's not necessary:
<QP>
Disabling Email Scanning does not leave you unprotected against viruses
that are distributed as email attachments. Norton AntiVirus Auto-Protect
scans incoming files as they are saved to your hard drive, including email
and email attachments. Email Scanning is just another layer on top of
this. To make sure that Auto-Protect is providing the maximum protection,
keep Auto-Protect enabled and run LiveUpdate regularly to ensure that you
have the most recent virus definitions.
</QP>
http://service1.symantec.com/SUPPORT/nav.nsf/docid/2002111812533106
4. Configure AVG as you wish via the User Interface | Tools | Advanced
settings
5. Check for and install any available updates.