Disabling part or all or Norton is seldom enough; you usually have to
uninstall
it instead.  You then often need to run this program to take care of what
the
uninstall left behind:

<http://service1.symantec.com/SUPPORT/tsgeninfo.nsf/docid/2005033108162039>

You sometimes even have to remove your email account under Windows
Mail, then restart Windows Mail and add the account again.

If this solves your problem, you may want a replacement antivirus program
that doesn't cause such problems.  McAfee and a recent version of Trend
are bad choices; they cause problems too.  I recommend either avast! or
AVG, either one with a custom install that tells it to leave out the part
that
scans email.

http://www.avast.com/eng/avast_4_home.html

http://free.grisoft.com/ww.download?prd=afe

On new computers, Windows Mail usually comes with at least one
message already in your Inbox, but not set up to download mail from
any account.

If you still have problems, we're likely to need to see the entire error
messages to offer much more help.  Right click on them and copy
them to your next message.