Is what several people have said about the ongoing intermittent, and now steadily worsening problems with my computer.

Once it's up and more or less stable, it keeps going. But it's acting like it's overheating, but the monitor program says that it's not RUNNING hot.
Yes, it IS likely a thermal problem, as all of the symptoms match "thermal problem"s.

How can that be?

Well, just on the assumption that maybe it is the motherboard, jmax315 and I (well, mostly Jmax who translated) looked online at the prices for motherboard upgrades. That way, even if the problem is something weirder, I'm at least getting an upgrade for my gamble.

So as we read online reviews of one model, we came across a curious thing:
The one fellow who was disgruntled was mad because the machine would run for a while and then, for no apparent reason, shut itself down, and then be difficult about coming back on.
Hmm. Exactly like what I'm experiencing (except now, even a cold intial startup at the beginning of the day is a wrestling match). His problem: the board had a defective thermal sensor.
I think that's what I have.
This is why the *initial* problem was mitigated by upgrading my fan and cooling. But it didn't go away, and the CPU is NOT running dangerously hot as a habit. At least that's not what the monitoring program says.

There are, in fact, problems on both the Windows and the Linux partitions, and those partitions are on separate hard drives, which doesn't suggest a hard drive problem.

Right now, it's running, and my plan is to leave it running until I leave for Spoutwood tomorrow. Today's 2 hour wrestling match to get it up and running was absurd.

So...
And we ordered the new Motherboard/RAM/CPU and my poor business bank account is now in ruins.
Sigh.

But if we're right (and we're both in agreement that this is the likely problem), then my pain has a definite $ cost to end. Well that and the inevitable PIOA for installation and troubleshooting...

A computer that just works. Why is that too much to ask?