I'm using an iMac Special Edition (graphite) running OS 9.1. According to
the System Profiler the DVD-ROM drive installed has driver version 1.4, it's
a Matshita revision number AA31, Product ID = SR 8184.

I've received a software manufacturer's CD-ROM with a software upgrade,
however every time I put the CD in the CD slot it sits there for about 5
seconds then ejects. I've tried other CD's and they work fine.

Short of the CD being a dud and I just simply have to get a replacement
(which is going to take ages so hopefully I won't have to) anyone have any
suggestions as to what might be wrong?

Cheers...Steven