First problem was a Blue Screen in Corel Guide section while installing the free Add-ons. Video became corrupt when Quick Preview mode was launched from the Manage / Tray. What's more.. Firefox browser became corrupt and had to be re-installed. It has something to do with Flash Player plugin.. me thinks.. to view Youtubes in Corel Guide? Just speculating.
Thought the system issues were licked, and re-installed X5 for a third time. Then spent 7 hours that day trying to fix. Nodda! Must have re-booted 30 times in the past week or two.
It may also be due to a DEFRAG utility. PSP when installed, and especially when creating thumbnails/databases scatters files all over the hard drive, and there are 1000's of fragments. So now PSP X5 and the defrag utility are gone. The machine (Win Xp) is stable again and all is well with X4. I wasted so much time with problems that it wasn't possible to try out new features.
So.. look at Corel Guide / Flash Player / installing freebies as the possible culprits.
-Ed