I have AOL Instant Messenger (AIM) installed on my Windows XP machine.
 It worked fine for a year.  Within the last few weeks though a
problem occurred.

Whenever someone IMs me the window pops up on my screen.  That's fine.
 But if I minimize the window after that that I never know when that
person IMs additional lines... AIM used to blink the title bar (is
that what it's called?) at the bottom of the screen.  Now... nothing. 
I have to go and open each AIM window to see if the person wrote
anything. This makes having a conversation next to impossible.

The problem might have started with an upgrade to the newest AIM - AIM
5.9.3690 but I honestly don't recall.

What have I tried to solve this?

I uninstalled and reinstalled AIM 5.9.3690.  No good.

I went and found an earlier version of AIM on the web at
oldversion.com.  I uninstalled what I had (5.9.3690) and installed
5.5.3598.  This is the most recent version on oldversion.com and it's
the version that works fine for a co-worker who uses an identical
hardware/software setup as me.

I, of course, scrutinized the "options" menu several times and looked
for something that would affect or control this.  Nada.

I google searched a little bit but didn't see anything promising.

I'll gladly pay anyone who comes up with a working solution to this
problem. I prefer to continue to use AIM, not Netscape 7's client or
Trillian, etc.

FYI, I don't know what the fix would be but the version of AIM (AIM
5.9.3690) is not the problem. I have the same version of AIM and am
running XP as well and do not have any problems.

Thanks for the comment... I doubt that AIM in and of itself is the
problem... millions of people are using this version of the client so
the problem would get fixed pretty fast.  And as you see above I
installed an older version that works flawlessly for my co-worker (and
probably worked fine for me -- I don't recall what my previous version
was.)