I'm guessing you've installed os3.9 on your a1200 from the amigaXL cd, which is a modified version of os3.9, made to work on amithlon/amigaXL. Your cd2 is your actual cdrom unit. the CD0 is an inexistant drive, hence the error when the device driver tries to access it.
So your solution should work just dandy.
Sincerely,
-Kenneth Straarup.
