after install, doesn't read disk 1 -1 reply

I've installed the game (3 disks) with no problem. I go to load it with cd1 and the message keeps popping up to tell me to insert disk 1.

Anyone know what to do?

hmmm.... your cd or dive could be dirty and unable to read the cd.

Thanks for your reply. Actually, I figured out to get the 1.3.1 patch. Post Edited: Doom III requires the disk to play. Please do not lead into discussions about ways around this.