Right. I've downloaded Memtest86. As the laptop does not have a floppy disk drive I downloaded the ISO image (zip). I unzipped it as instructed and after some trouble (another blue screen along the way) burned the unzipped ISO file to a CD. I then restarted the computer with the CD in the drive, double clicked on the file and was told that Windows could not open it.

Stuck again. Sorry, folks, but what programe do I need to open this file and run the test?