[robespierre]

I have a CDROM on my O2, and it fail on read some blocks of data cds, don't read some cdrs and this behavior is the same as the CDROM before it on that system(don't read randomly). It's a Toshiba and has a jumper on him, Coud i take the jumper off to try if this is the problem? Also i will try to change the SCSI cable...This problem Is very odd, i can't install IRIX on him, got reading errors, and can't finish instalation.

You should start a new thread for your question, it has nothing to do with the subject of this thread.
Changing jumpers around is not likely to help your problem, but I guess you should try easy things first.
Failing to read CD-R is a sign that laser optical power is out of adjustment.