V4 MAtrix Infinity - Discs not loading

[oZER0o]

I've put an infinity in a v4 ps2, but it doesnt seem to want to boot into the firmware cd. it boots normal retail ps2 games but only after a few seconds on the browser. i tried a ps2 backup and it gave the red non-ps2 format disc screen, same for the inifty firmware disc.i think the laser might be bad or something, it could even only need a clean. i think this is quite strange.....

the matrix logo comes up when you power on, and i can access the infinity options page with circle and triangle on boot, its just this disc loading milarky
anyopne got any ideas?

any help much appreciated. my mate is getting impatient, he wants his ps2 back! lol.
cheers,
zero

edit:

also plays ps1 originals fine, again, takes a little time reading the disc but then all is well. do you guys think i should adjust the laser height, and the cd and dvd pots? just an idea. tbh, i dont think its much to do with the mod, if its playing games fine, the mod is probably putting a little more stress on the laser and it might need adjusting? im no expert, you guys give me your opinions. LUFCfan im pointing at you, hahaha. cheers dudes.

edit 2:

after cleaning the laser we have slight advancement, in the browser when a ps2 original is in, it eventually comes up with "playstation2 disc" after a while, but for any backup games/infinity firmware cd etc it brings up the old disc read error. definetely a laser problem ?