Microsoft's freeware Windows Memory Diagnostic is a misnomer with limited usefulness. But, I'm mentioning here since I actually used it yesterday to help figure out a problem. Its name is a misnomer since it doesn't run under Windows at all (which makes sense for a hardware memory diagnostic app). The EXE you download asks if you want to create a floppy image (what PC comes with floppies these days?) or a CD-ROM image. I opted to create the ISO file and burned to a CD-R disc. Booting it brings up a DOS screen with the running diagnostic. The diagnostic is of limited use since it takes quite a while (many minutes) and requires you to actually sit in front of the display since it doesn't appear to keep any history or flag alerts. Once an error scrolls up and away you have no indication of any error that might have been listed. That said, I did sit in front of the screen for many many minutes and saw the error (red line in the screen shot above). The error message is actually pretty vague and nearly useless for most people. But, at least it indicates something is wrong. And, with a bit of head scratching and detective work, I figured out the problem.