Hi Pinsel,
I would check Preferences - File Locations to see if PSP8 has been pointed to the location of the plugins that are working with PSP7.
Ads is right about regedit - not something to be fiddled with lightly - but re-installing PSP clean with no other programs running might fix the registry problem.
BTW *
great* avatar! You have to like a fellow who, despite his handicaps, is selflessly ready to perform "prodigious service" in the mine-shaft world of the future!