I assume that you clicked into the VM window and pressed a key when the VM prompted you to boot from the CD/DVD? (yes, its a stupid question, but you won't believe how many people fail to do that by waiting too long.)

What guest OS are you trying to install in the VM? (with version, please). I'm assuming it's some flavor of Windows by the prompt, but it's nice to be sure. 

Also, what version of Workstation are you using on what host operating system?