Hmm.. I did a little googling and came across this site: http://www.alcpu.com/CoreTemp/
I can't really help you out about the program since I've never tried it, but it seems pretty good. Plus, it is free. Try to make a note of the component temp if/when your computer restarts..
As for your room temp, a good operating temperature for a PC is about 60 to 75 degrees Fahrenheit (15 to 24 or so Celsius). Cooler than this is of course, better than warmer. Operating a PC in a hot room that is over 80 degrees Fahrenheit can make it very difficult to cool. *(http://www.pcguide.com/care/care/gen/envAmbient-c.html
I work for a school board, and all the server rooms and computer labs are generally very cold... Hopefully it's something simple like this, otherwise it may be a power issue, like a short of some sort.
-THE LEGEND x7x