Hi
i'm using mac pro 2.66 Quad core with 3 GB memory.
my optic drive is : OPTIARC DVD RW AD-7170A.

i'm trying to install logic pro but when i insert the dvd installation disc it spits it back out after 20-30 sec..
i've 8 discs of installation and non of them is readable.

when i put regular dvd or cd i have no problem.

also, i have a macbook pro and when i insert the dvd installation disc its ok and can be read by the optic drive.

anyone have an idea of what to do or get across by the same problem and fix it?
thanks
Niv