Webroot Spy Sweeper is an antispyware program instead of an antivirus
program, so that avoids the problems caused by having more than one
antivirus program installed at a time. However, there is a version of it
that
has an antivirus program included. For the antispyware part, just telling
it to disable the part that scans email should be enough to prevent it from
causing problems in Windows Mail.
http://thundercloud.net/infoave/tutorials/email-scanning/index.htm
A recent version of the Trend antivirus program is one of the three
antivirus programs that cause the most problems in Windows Mail..
Just disabling part or all of it seldom helps; you usually have to
uninstall it instead. You may then need to remove your email
account under Windows Mail, then restart Windows Mail and
add the account again.
Also, click on the Outbox, then Current View, then Show All
Messages. If this shows any messages you haven't succeeded
in sending, either move them to the Drafts folder or delete them.
If you find any that refuse to do either, download and install
this hotfix, with Windows Mail not running:
http://support.microsoft.com/default.aspx/kb/941090
Although it's labelled as for mail stuck in the Outbox, it also
works in other folders. If you don't know whether you have a
32-bit version of Vista or a 64-bit version, try the hotfix for
the 32-bit versions first. The Vista SP1 update includes this
hotfix and more, but takes longer to install.
If this solves your problem but leaves you with no antivirus
program, you may want a replacement antivirus program
that doesn't cause problems in Windows Mail. The Norton,
McAfee, and Trend antivirus programs are bad choices;
they are the three antivirus programs we see causing problems
in Windows Mail the most often. I recommend either avast!
or the free version of AVG, either one with a custom install
where you tell it to leave out the parts that scan email.
http://www.avast.com/eng/avast_4_home.html
http://free.avg.com/ww.download?prd=afe
