Curious problem after updating video drivers, PSP9 and X don't display.

Here's one I've never seen before. I'm seeing this on a homebuilt rig,
it's an A64 X2 4800+, 2 gigs of PC3200 at dual channel, nVidia 6800GT AGP
256 meg vid card, XP Pro SP2 (clean install, it's a new build). Was
running nvidias WHQL 77.77 Forceware set with no problems I was aware of
anywhere. PSP9 was one of the first apps I installed when I got the
desktop up and it's patched thru the latest. Last week I downloaded and
installed the PSP X trial. This week end I picked up a couple of new games
and figured I'd best upgrade my vid drivers to accomodate the newest
features, et al. That stuff worked fine. The new '80' series Forceware
drivers do better with my dual core cpu and some other things. But when I
opened both PSP 9 and X, neither one appeared on the screen nor on the
taskbar. But both were running in the task manager under Processes tab,
neither were in Applications tab.
I thought to kill the PSP processes, that was ok. Then I thought to
uninstall/reinstall PSP X as it would be the easiest with only 1 patch to
deal with. Nope. Uninstaller flat froze up. Rebooting was the only thing
that killed that window. OK, so I tried uninstalling PSP 9. Same thing.
The uninstaller froze up. It appears that PSP must run the executeable
during the uninstall process somewhere, because in both cases I found the
PSP executeable running in task manager in the processes tab. I can run
every other graphics application I have and also 3D tools, including Adobe
Elements 2.0, XSI and Mod tools, Painter IX trial and Painter Essentials.
But Paint Shop Pro 9 and X will not display at all.
Since I'm not going to be without my PSP's, I rolled the system back to a
restore point just before installing those Forceware 81.85 WHQL drivers.
This worked well. I tried installing the new drivers again. I worked with
this half the day yesterday and finally gave up and am back using the 77.77
drivers with everything running fine.
Any ideas on this problem? Since it appears to only adversely affect PSP 9
and X I thought to ask here in a Corel ng, and will also post this in the
usenet nVidia ng.
TIA,
McG.