If reformatting didn't fix it then it shouldn't have anything to do with the registry. Are you sure it has been completely reformatted? (old partitions completely deleted) Those errors do seem to be something to do with software, but a reformat should have fixed it.
You could try running either memtest 86 (http://www.memtest.org/
) or memtest (http://hcidesign.com/memtest/
) to check for problems with the ram. Doesn't seem to be a likely cause since I doubt the computer guy could have missed it, but still worth a try. Ohh and let those programs run for a while (say 2-3 hours) to be sure.