WinXP screen resolution problem when changing users

Hi all,

I've tried to search the archives, but found nothing on this...

I've got a Compaq Deskpro 2100 laptop with Windows XP. I bought it
less than a week ago, pre-installed.
It works fine, and I've defined two users.

When I change from one user to the other, the display changes to
600x800 or worse. First time I managed to set it back to normal, but
not second time.

So I'm stuck with a screen covered in enormous graphics, and very,
very ugly. :-)

I've seached the MS website and done more general internet searches,
and found nothing.

Anyone knows anything about it?

Thanks!
-- 
JRobinss