Hopefully my solution will help others. I have a MacBook Pro on which I am
running WindowsXP Home Edition. It is running totally separate from the Mac
OS. I have to reboot to switch between OS's. After running my system for
about 3 months successfully with a combination Microsoft wireless mouse &
keyboard, I developed the common screen saver will not start problem. I tried
everything in the community newsgroups I could find with no success. I then
realized the uniqueness of my situation and solved the problem easily.

I often take my computer to the office and set it down on my desk next to my
desktop system. For some unknown to me at the time reason, I kept getting a
couple of "found new device" messages each time I started my MacBook in
Windows. I ignored and bypassed these messages for several weeks. However, I
finally got tired of the messages and decided to see what would happen if I
responded to them.  I should mention that these were an HID keyboard and an
HID mouse that were found. I later realized that my laptop had seen the non
Microsoft, made in China keyboard and mouse that were part of my desktop
system.

My mistake!! After installing the new HID's found, I developed the above
mentioned screen saver problem plus a couple of other annoying problems. As I
previously mentioned I tried everything. It finally dawned on me that I
should just uninstall the HID's that had been installed. I tried to do this
through the device manager, but I couldn't quite figure out how to do this as
I seemed to have under Human Interface Devices several HID's that were
needed. I didn't initially think to just uninstall these devices under the
Keyboard and Mice devices.

When I finally realized what to do, I uninstalled the HID's under Keyboards
and Mice.  Everything now works great.  Hope this might help someone.