I’m happy to report my computer is no longer overheating. 
A co-worker of mine suggested I check the thermal compound; sure enough, it was toast, so I walked down to Fry’s(again) and picked up a small tube of Arctic Silver. I followed the instructions given on their website and 30 minutes later things were much cooler.
It amazes me that a drop of liquid no bigger than a grain of rice can make such a difference in temperature.
Thanks for the tip Pat!