PSX1 games "jump" on my PS2 with Messiah...

[Calfie]

I`ve got this annoying problem with every PS1 game I use with my Messiah2 modded PS2. Every game (be it PAL/NTSC and original/burned) sort-of "jumps" up and down at a fast rate. It`s not big jumps and it CAN be ignored but its annyoing as hell. So is it a case of a wronly installed chip or? Any solutions?

(It`s not the TV either, tried different TVs as well...)