I finally diagnosed my own problem. After the first computer died, I scavenged the ram to install into the 2nd. My OSX purchase was a single disc and didn’t have the hardware test disk anywhere. I also understand that Apple doesn’t carry those anymore. I went online and downloaded Rember, a ram testing program, and was able to find the bad module through elimination. It was the same ram I had brought from the first. Now I probably own two good g4s. So far, so good as I’ve had several large ram eating apps open at the same time and no freezing, crashing or disappearing hdds. Hope this helps the next guy!
Chris