Repost:
Run a *thorough* check for hijackware, including posting your
hijackthis log
to an appropriate forum...

wonkywidget wrote:
On Thu, 23 Oct 2008 20:22:29 -0400, "PA Bear [MS MVP]"
wrote:

Assuming email scanning is not installed or enabled and you can send
yourself emails OK, the problem isn't likely to be on your end...

Sorry, forgot that little detail...the same thing happens even when I
send messages to myself! When I scanned for viruses, I had the hard
drive hooked up externally to another system to take away the
possibility of any background processes hindering my efforts. I
cleaned out all the temp directories prior to scanning. Some system32
files like, winlogon, userinit, explorer, lsass and svchost were
infected and needed to be replaced. After that it worked for a bit.
Then I put AVG back on(again minus the email options), again it
stopped working. Took AVG off, still no go. Outlook's safe mode
doesn't help, neither does booting into safe mode with networking. I
can try hijack this but I'm pretty confident my scanning method
removed everything. It'd be cool if there were a registry fix or
something *lol*

I ran a virus scan on the hard drive and cleaned off several
infections, maybe some unwanted modification was left behind that
needs to be corrected?

...unless you have more work to do.

Unexplained computer behavior may be caused by deceptive software
http://support.microsoft.com/kb/827315

Run a /thorough/ check for hijackware, including posting your
hijackthis log to an appropriate forum.

You are probably scanning outgoing emails with your antivirus and/or
other programs. Turn that off and the problem will very likley go away.
Once a mail client hands the mail over to the AV for scanning, it
considers it Sent. If the AV fails to get it out in time, the window of
time closes and it fails to get sent.

HTH