I searched the 'net some more, and found the actual error: "Power Surge On Hub Port. One of the USB device has exceeded the power limits."
Anyway if you really wham and wiggle something into a USB port you can break it and short it out and potentially the rest of the system too.
So it would have to take "effort" so to speak? That couldn't have been the cause then.
Boards go faulty and if there was a fault out of the box with it you'd have known about it.
Well, the only USB device hooked up was a printer, and before this desktop, it was hooked up to the USB port of a Laptop for over a year with no problems. Thus, I don't believe the error actually has to do with USB. Also,
the desktop won't turn on at all now - as if there's no power. The power cables are all secure, and the PSU is the PC Power and Cooling brand - very high quality and only 6 months old. I think the only explanation is that there was a fault in the board, but I just didn't pay enough attention to it.
So I guess I have some shopping to do. Of course, I really want to know if there's something I'm missing here, or if someone else has had this problem and found the specific cause. Thanks for your help, Neil.