Stop Error - ACPI BIOS not compliant

I have a Dell Dimension 4400.
Did a simple remove Cd drive and replace with DVD NEC-2510 drive that was in my other Dell Dimension 2400 PC.
When I rebooted it gave me froze at start up saying PC didn't shut down correctly. I click last know config and it freezes. So I removed the DVD drive and replaced with the CD drive and same thing.
then all of sudden I get the blue screen error 0x-000000A5 ACPI not fully compliant. I did all the resets to defaults, and nothing. Even tried to reload XP and get the same error.
Hit F7 during new install and still get blue screen error.
Any suggestions?

Have you tried putting the original ROM back in to stabilise the system? OEM machines such as Dell's have their software and hardware married together in very strange ways and you tamper at your peril. Find the Service Tag on the case and input that down at Dell's site and you'll find out exactly which CD ROM you can use to replace yours if it's broken and you can seek one out on e-Bay or similar. For the time being, though, the only way to get back to a working system is by putting the old one back in.

All solved and not sure how.
I re installed Windows for a 4th time, before I did I took out the memory cards and put them back in. I guess that did it.
All installed and new drive is working.
Now the 5 year old has a PC.
Man remember when we were 5.
Home PC's were not out yet.
What a world!