Sounds like you have more than one CD drive. Have you tried to narrow things down by troubleshooting with only one of the drives installed at a time?
When you say "they shut down", to you mean that the system just powers down by itself shorlty after it finishes loading Windows, or do you mean something else?
DMR
Wombat At Large
7,229 posts since Dec 2003
Reputation Points: 221
Solved Threads: 370
The BIOS issue makes me think this isn't the problem, but here's a link to a common cause of disappearing CD drives:
http://support.microsoft.com/kb/q270008/
Although the article pertains to Win 2000, I've seen the problem occur with XP as well; the fix described for Win 2000 works for XP.
Please note that although the article only refers to the "UpperFilters" and "LowerFilters" entries in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet registry subkey, I've had to apply the fix to the similar entries (if found) in any other HKEY_LOCAL_MACHINE\SYSTEM\ControlSet00x subkeys as well in order to make it work.
DMR
Wombat At Large
7,229 posts since Dec 2003
Reputation Points: 221
Solved Threads: 370
To be honest, I don't remeber if there normally are .BAK entries under those subkeys. Just delete the keys exactly as instructed in the link I gave and see if that does anything to help the problem.
DMR
Wombat At Large
7,229 posts since Dec 2003
Reputation Points: 221
Solved Threads: 370
Here's a link that lists the power usage (in Watts) of common computer components; use it as a rough guide to see if your power supply's wattage rating measures up:
http://computer.howstuffworks.com/power-supply3.htm
If you've only got a 250W supply, and your machine is relatively fully stocked with components, I'd get a beefier supply.
Of course, if the power supply is of sufficient rated wattage but just isn't providing as much "oomph" as it should, that's a different story.
One thing to remember about weak/failing power supplies (or weak batteries, for that matter) is that they will often appear to be putting out the right voltages if you measure them with a voltmeter, but will not be supplying enough current, and current is a bit more difficult to accurately measure than voltage.
Before you go out and pay for a new power supply though, replace the IDE ribbon cable on the CDs with another cable that's known to be in good, working condition if you haven't done that already. Also, it is possible that the IDE channel that the CDs are connected to is faulty, which would be a bummer- there's not much you can do there except replace the mobo...
DMR
Wombat At Large
7,229 posts since Dec 2003
Reputation Points: 221
Solved Threads: 370