Warning: A problem with the cooling system has been detected. Please turn off the computer immediately and return it for service.
Needless to say, it scared the crap out of me. I immediately turned it off and thought that my machine was toast.
I operated it entirely the next day without a warning. This morning, the innocuous dialog box with the same message popped up.
The thing was pumping out heat from the fan. I immediately got a can of compressed air and sprayed every orifice under the laptop. Dust and crap and all sorts of stuff came out. I was amazed at the amount of dust and particulate matter that spewed out.
I then googled the problem on another device, and came up with this URL : http://botcrawl.com/warning-a-problem-with-the-cooling-system-has-been-detected/
This URL suggested that uninstalling the Toshiba Value Added Package. I did this for good measure, but I noticed that after spraying the compressed air and getting all of the dust and junk out, the heat was no longer being pumped out of the fan ports.
My laptop does run cooler now. Prior to this I had never used the canned air to blow out the dust, but I did notice that my computer would definitely run hot out of the fan port and it now runs cool.
All this to say is that I solved the problem. I think that it was a bunch of dust and crap accumulated in fan assembly, because my computer runs cooler. Problem solved without a trip to repair shop. I am going to keep a can of air around and regularly give the holes in the underside a good shot every once in awhile.