TBird Issues for Midrange

I had loads of fun this weekend. After Thunderbird (7.0.1) asked me if I
wanted to update the Lightning plug-in (which, by the way I don't remember
installing in any version of TBird), I said, Sure, go for it. May not be
related but ever since then TBird has not worked on my weekend computer.
Oh, I forgot to mention that Lightning does *not* show up in the plug-in
section of the Add-Ons tab of the Tools menu.

By "not worked" what I mean is that every time I try to send a new email,
reply to or forward an existing email, the "Sending Mail..." progress box is
displayed with "Status: Attaching" even though I didn't attach anything. I
left one test running from Saturday at 1400 to Sunday at 0830; still
attaching - nothing.

Here's what I have done. Started TBird in safe-mode. Same problem.
Uninstalled TBird. Downloaded the current version and installed it. Same
problem.

Contacted Mozilla support. I was educated that the profiles for TBird are
not removed when it is uninstalled. So I used the MozBackup program to save
the profile (just in case). I manually saved my addresses to a csv file and
an LDIF (whatever that is) file. All important emails were saved to a
folder.

Uninstalled TBird, again. Deleted the profile. Re-installed TBird from the
previous day's download exe. Trieds to start TBird, but was told it was
already running. Couldn't find it in the Task Manager's "Applications" tab
and have no idea what it might be in the "Processes" tab (certainly nothing
intuitive). (Side note: I ran TBird on another computer and it shows up in
the "Application" tab.)

Anyway, I re-booted the PX (XP Pro at SP3). Still telling me that TBird is
already running. So I restored the profile from the MozBackup. TBird loads
- but the @#$% "Sending Message..." progress box keeps says "Status:
Attaching" and won't go away.

The one idea I have not tried (and probably not one that will have a
positive effect, in my feeble opinion) is to actually install the Lightning
plug-in. Unfortunately, I have to go home and mow the yard, weed whack, and
beat my head again a brick wall.