I suspect the problems are unrelated. The PSR2000 buttons wear out. You need to get an electrician to solder in new contacts. While you're at it you should replace all of the fill buttons. While the keyboard is open, you can clean up around the keys.

I had this problem numerous times when I owned the PSR2000/2100. Luckily, I had a high school aged geek friend who would fix the keyboard at $20/hr. The three times I had this problem, it took him just one hour.

Beakybird