I hadn't updated my system in a long time, it ran fine so I didn't worry about it. I'll let ya know what I think about the update tool.
I'm positive it was a bad DIMM - I removed one DIMM and the problem remained. Put it back in and removed the other DIMM and the problem cleared up. I'll probably put the new kernel in anyway since I'll have 1GB once I exchange the defective one.