Help!

About 6 weeks ago I started experiencing situations in which all or part
of my outlook screen would turn negative while reading or composing a
message. By "negative" I mean that instead of black or blue characters
on a white background, the background would turn solid black and the
characters would turn into some inverted color (hard to read; I very
often have dark blue letters on a black background).

This almost looks like it could be a driver problem, but it happens in
no other application besides Outlook (2003). There was no specific
change in the system that I am aware of which accompanied the onset of
this, it happens sporadically (I'd say about 15% of the time at most,
perhaps less) and I can "fix" the problem by typing the in "negative"
area, but if I scroll the screen, the new text often comes in from the
top or bottom in "negative" format.

Anyone have an idea what might be causing this? The system is XP Pro,
and it's clean (I am an IT professional with a number of certifications
and I teach college level IT courses, so I'm not a novice or newbie).

Thanks,
Barry Watzman