OK, battery replaced this morning and it appears to have fixed the problem.
Thanks!
I found my wrist strap for grounding myself to the case (yes I am schooled in ESD so use it religiously when working inside my computers) has undergone some kind of self destruct phase of disintegration. The cord has some kind of blue goo all over it and the insulation is falling off/cracking all over the place.
Anyone know what's going on with that?
At first I thought I might have a spare battery leaking in the drawer I keep it in but that's not the case.
I assume I can get another cord/cable to snap onto the wrist strap portion which is in good shape, albeit old.
Replacing the battery was easier than expected too. Online said I'd have to remove the video card. Nope it was in plain sight with no obstructions in the way. 5 minute job once the computer was unhooked and on the bench.