ACPI Error from memory upgrade in Windows 2000

I just upgraded the memory in my Dell CPxJ laptop from 128mb to 256mb. I had to update my BIOS, but when I did everything worked fine. For one day. Then I started getting the blue screen with the ACPI Stop Error.

I have:

Removed the new memory stick. The machine worked fine.
Replaced my existing memory stick with the new one (in DIMM A). The machine worked fine.
Put the old memory stick in DIMM B and the new one in DIMM A. I got the Stop Error.
Put the old stick in DIMM B with nothing in DIMM A. The machine wouldn't boot.

Any advice that anyone can offer would be greatly appreciated.

 

Try a different brand of RAM. Sometimes RAM modules can be incompatible with each other. Get it from crucial.com.