Not reading DVD back-ups or originals

[cactus]

I got my brother in-law's PS2 modded with a Messiah 2 chip and we just tried an original DVD game and and DVD copy that work fine in my system. 9/10 times, the game won't load and when it does, there is freezing and loss of sound after a minute or two. I think we might need the laser re-calibrated and didn't think it would be the chip since all CD-R games work fine. Any suggestions? I remember reading about re-fixing the laser and just wanted some advice. He's only had the system since Christmas and was thinking of returning it for a whole new system...minus his chip, of course!

[Hull_chipper]

Run a cleaning disc thru it m8 - I know tis brand new but, needs doing on a lot of machines at the mo.