Dissapearing CD-ROM

First boot computer and press key to enter the CMOS configuration and check the bios is recognizing the drives
Open device manager and check the configuration for any IRQ conflicts and that the drives are listed,check each drive for performance andalso that the controllers donot have an exclamation marks.
You may want to use startup disk to reload the system files,in case the Autoexec.bat file is corrupt

Try to restart yout computer in safe mode. There is no CD-ROM support in safe mode, just check in device manager if you can see CD-rom & Zip drives.

Alex

the only way i can think of fixing this is to reset your pc and then go the cmos settings and make sure when u do the test that that it picks the cd rom up.
one simple reason might be that the plugs inside the computer have accidentily come off the pins.

okay bev here we go.
first right click on my computer and choose properties from the menu. this should give you the general tab of the system properties. please click on device manager tab. if you see yellow ?'s or red x on primary /secondary ide controllers continue if not skip the rest of my post. if they are splatted (the tech term for the yellow ? OR red x you need to pull a key in the registry... this may or may not work so i hope you have a backup done. navigate in regedit to hkey local machine\enum select and delete the mf key. close regedit and restart the computer (start shutdown and then restart). when you reboot new hardware should be located. if it is windows may suggest that you need to reboot to continue setting up changes SELECT NO when you are all the way up into windows restart as above this may take up to three restarts.

good luck!