Fred, I wanted to pay along my thanks for reminding me and your readers about the Microsoft Memory Diagnostic tool ( http://oca.microsoft.com/en/windiag.asp ). I had been fighting a blue screen of death on every bootup for a long time. I had changed out just about everything in the computer, even stripping it down to the bare essentials without fixing it. I did find that if I let the computer run for about 5 minutes and then rebooting would bring it back to life. To shorten the story, I downloaded the memory tool, checked the memory and found the 2nd memory strip to be bad. A quick replacement and I’m back to normal. I’ve worked with computers since the Radio Shack Model Ones and I’m always learning new things, especially from your Plus edition. Thank you once again. —Mike
Glad it helped! RAM is usually very reliable— so much so that many RAM configurations lack the "ECC" or "error correcting circuitry" that all RAM used to come with. The upside: Non-ECC RAM is less expensive. But that means that when RAM goes bad, you experience the errors directly, without warning, without correction, and with little recourse. And, as Mike found, you may be left with few clues as to what’s wrong.
The free Windows Memory Diagnostic is useful as a periodic check to ensure your RAM is OK; or as a troubleshooting tool when things are hosed. But it’s also only one of a number of similar tools.
Just about every PC ever made has at least a basic RAM-testing tool built into the BIOS ( http://snipurl.com/of6i ). The nomenclature differs, but it’s usually part of a "full boot" or "extended boot," or non-"QuickBoot" or some similarly named option. It enables a more complete, more-thorough power-on self-test ("POST"). You usually can see the BIOS-based RAM test in operation when it’s enabled: At boot, the on-screen display shows the system counting up through RAM, checking it megabyte by megabyte, two or three times. It’s only a quick and dirty test, but— as most PCs have no other built-in way to check RAM— it’s better than nothing.
And, of course, there’s other RAM-testing software available, including the venerable (and still free) MemTest86: http://www.memtest86.com/