Thanks for replying. The problem started with only one PC accessing the
account. After a couple of days and failed efforts by AT&T support chat and
phone call with Tier 2 support telling me problem was in my computer, I did
put my wife's account on my spare computer, also running Windows 7 Home
Premium & Windows Live Mail, and the problem also occurred on that machine.
When I close Live Mail, the download dialog box just continues to run on with
supposed/phantom downloads (none actually show up in any mailboxes) going up
in the 10s of thousands before I clicked Stop.
To further troubleshoot, I set up a new AT&T sub-account e-mail address,
added it to my wife's computer (where problem started), unchecked "Include
this account when receiving mail" on her original account to stop it from
downloading and checked "Include this account when receiving mail" on the new
account/e-mail address. When Live Mail was run, the new e-mail worked
properly, downloading some test messages I had sent it, and when Live Mail
was closed, there was no longer a run away download going on. I again enabled
the old e-mail and opened Live Mail, closed it and had the run away download.
I am pretty much convinced this has to be an AT&T server problem, but if
anyone has any other ideas I could try, please let me know. In the mean time
it will be back to calling AT&T 2nd Tier Support.