Windows XP PRO Screensaver problems

Hi.
In the beginning everythink was fun, XP was working. But later after i had
an upgrade, the screensaver stoped working.
First on my site as administrator, then 3-4 weeks later the same problem was
at the other username acount.
I have installed service pack 2 and hoped that this problem was gone, but
no. Is there a file i can install to fix this problem? What can i do?

Regards from
Acidburn