PS1 mod chips

[keysie]

The strangest thing has happened to me.
I've just chipped a PS1 with a four wire mod chip.It plays all my backup cd's fine. No problem there,or at least so I thought.
When I tried to play an original game the damn thing would not recognize the cd. I've tried all the originall games that i have, and none of them work.,although they did before chipping.
How can that be. Any help greatfully received.