Apple Hardware Test error code?

Hello all. I've been having frequent freezing problems with my iMac G5 for a while now. There doesn't seem to be any rhyme or reason to them; it doesn't matter what program I'm running, or how many programs are running -- sometimes the program itself will quit for no reason (sometimes I'll be able to restart the program, and sometimes it will continue to crash, until I restart the computer), and sometimes the entire computer will freeze up, and either tell me that I need to restart, or some rather alarming text about kernel panics will appear on top of the desktop.

I tried running the Apple Hardware Test, twice, but I got the same error message each time, almost as soon as the test started. I was hoping someone here would help me decode it:

2STH/1/3:CPU T-DIODE

I've basically resigned myself to the fact that I need a new computer, and indeed, my interests and ambitions require a computer that has a bit more oomph than the one I've got now, but while I'm saving for my dream machine, I was hoping I could do something to help this poor, tired iMac continue to limp onwards for just a few more months.