I ran into that problem, and I tracked down and dragged over every Photoshop file and Adobe file I could find, even searching for invisibles. Nothing worked. Maybe I keep missing something, but I had to reinstall from the disk each time.

I run Photoshop 7, not only because I'm too cheap to upgrade but because the same version runs in OS 9. Copying the files doesn't work in that case, either. It appears to have very tight anti-pirating routines built in.