about a year ago my buddy ask me to order him a modchip. he opted for the magic series. i sent his brand new ps2 to a very reputible installer.
his new ps2 had to be rebooted a couple of times before it would boot a backup.
i contacted the installer and he said thats semi-normal when you use a cheap chip.
i would clean the laser and try booting some dvd-r movies with the chip turned off. this should let you know if its the chip or the laser.
my 2 cents
v7 with messiah2 v 1.31
v9 unmodded running mc exploit