"New" backup problems

[JIK]

I've been backing up my PS games for about a year now and never had a problem. The last 5 or so games I've tried to make a copy of just won't load in my PS One. I'm using the same settings now as before. I can still play the other games I've copied.
I've tried to make backups of both older and newer games (like Tony Hawk 3, Tekken 3, Need For Speed Porsche, Moto Racer - World Tour) but there's no difference -> it just stops at the white start screen...
Does anybody have an idea what could be wrong?

Please help me,
JIK