Installer not recognized

I have a Windows 2000 system that does not launch installer programs. I will pop in a CD and go to Start->Run and enter the setup.exe and the CD will start to spin but it then stops and the system goes idle. There’s no freezing up, no BSOD and everything else continues fine. I just can’t install any new applications. I’ve tried starting and stopping the installer services and stopping any virus protection programs and services as well. Any clues.