Well, your secret is safe, for now!...
And there was no system specs in the pdf. If you think it is a hardware issue, then start removing things until the error goes away. I'd start with the RAM. Just make sure before you start to check if this Mac has to have RAM in pairs or not. If it's not the RAM, pull any cards that may be in it. If that doesn't work, then see if you can find the CDs that came with it new, as there will be a hardware check CD in the bunch. Run it and see what it says. I did have something like this once, and it was hardware, as I had installed 3 different versions of OS X erasing the hard drive each time, and it didn't fix it. Lucky for me, there was a warranty on the Mac (it was used, and I had 60 days) and they swapped it out for me, and I have had no issues with the replacement. If it's the CPU, video card, or motherboard, depending on the Mac, you may just need to get a new one.