I'm having a similar problem: When I OPEN pec, it says: "Access violation at address 00403B80 in module "PEC.EXE". Read of address FFFFFFFF."
Then, pec opens and all the games are there, but each time I select a game, I get the same message. And when I close it, I get the "There was an error writing to the registry" error. I tried reinstalling the program, but it didn't help. I'm downloading the most recent version of the game, hoping it'll help.
Also, when I try to detect the game I have in my CD-Drive, it tells me the game doesn't exist, including it's number. But Half an hour ago, it worked fine and it detected it fine. It bugged after I closed everything (after having played Legend of Dragoon for a bit) and when I tried to get back, it started giving me this error.
And I don't want to just change my cheatlist cuz I added many games in it and I don't want to lose them (I don't remember which ones I added/modified, except for a few, like FF9 and Monster Rancher)