PS2 burning question - HELP!

[deet]

hi i just got my ps2 modded, don't know which chip, but they said i can play all backups even EA sports, anyway, i've been burning these backups which i assume are patched already, and they all load halfway and then the unit freezes!, i'm doing the gameshark thing loading it with R1 and O button. it loads, then freezes before i can play anything. i've even burned at 1x on CDRWin and used different brand CD's. Anyone have any ideas! PSX stuff works fine. Please HELP!!!