If it occurs at start-up, I'm guessing it's a hardware error. Looking at my book it seems that all the hardware errors are memory errors? Gonna guess at some problematic/dead memory chips. Thing is, if that's true, you'll have to find new chips to replace any that are bad. Does anyone know if chips can be removed without causing it to not boot (ie, if it's wired through)? I can't be sure and if someone would like a photo/scan of the page to get a better idea, I can do that.