It's odd. I'd been using this as my primary for perhaps two years, then stopped as I'd gotten a newer one. Hardly used it at all for the next year or two, recently used it a bit again. No issues, decided to reinstall XP, and halfway through reinstalling the software this began to happen. I thought nothing of it, and ended up installing Win7 as an upgrade, but that pesky orange light still refused to turn blue again. Almost seems like too much to be a coincidence, but it could be. As you say, I've reinstalled all software I can think of.
I had actually begun opening up the laptop at one point, but have had a few bad experiences doing so where the display simply stopped working (must have loosened one of the extremely fragile wires) and was never able to restore function, so I'm hesitant to do so without seeing a full teardown first.
Which it looks like I've found, actually. So I guess I'll open this sucker up and see what I find, and am able to accomplish.
Thanks again for all the assistance with this. Truly appreciated.