Hey Tony, thanks for the feedback. My apologies. I should have mentioned that the battery isn't installed. It isn't the original but is completely dead. I didn't think it was important when I was describing the situation above, but I guess I should for the sake of completeness. This problem first asserted itself a couple weeks ago. The laptop would shut down after being on for several hours, but it would always start back up. When it shut down, I felt around the bottom, expecting to find it would be very hot, but it wasn't. Ťhen, a few days ago, it wouldn't restart, behaving like it does now. I removed the battery, thinking it might be draining the PS. That seemed fo take care of the problem. But it didn't last. Then I tried something that would work with another laptop I owned, when it would spontaneously shut down. I used compressed air to blow all the dust out of the inside. That seemed to help too and things seemed back to normal for a couple of days. Then yesterday, when I went to start it up, nada.

So, yeah, I tried a couple of different things, each which seemed to help until it didn't.