CD drive won't work; iMac G4 700 15" LCD

[cameramandoug]

I have a iMac G4 700 15" LCD, 40 GB HD, 512MB RAM, CD-ROM drive....running OSX Panther. I have forgotten my user password....the machine boots up to the login screen. I tried to put in my Install disc to boot from that, but the CD tray will not open. I restarted and held down the mouse, that forced open the CD tray, but when I put my install CD in, it loaded and I heard it trying to read...but after about 10 seconds it just pops back out. Can anyone help? Is my CD drive gone bad??? Can I boot from an external device? I have an external firewire DVD drive and an older G3 iMac that still work great, could I use either of those to boot from?

Any help would be greatly appreciated!