Help I have major problems..

Just installed Panther on my quicksilver 800 with the drive that came with the mac.

Then i just sold my PC which had the Pioneer 105 in it, and reinstalled it back in the mac. Have been there a couple of month ago under jaguar, had no problems there..
But now Panther can see the drive but when i put a cd or dvd in it just says it can't read the disc..
Have had the dvd-r back ina pc to downgrade the frimware and tried every one no luck???? It also runs great in my friends pc....he hopes it can stay there....but need the drive in my mac for all my home movies...

Hope someone can give a little help