I ran my scenario again, and it failed again. Temperature was around 75°C at the time. So I thought about what I was running in software that might contribute. I was running a beta of GameBooster (v 3.5) so I uninstalled it to see. I ran a single EC44 in free roam the entire length of the CSX Mainline from West to East. Took about 4 hours, but it finished without failure. Then I re-ran my scenario, and it failed again at the same approximate location. The video below shows what happens:
http://youtu.be/_TSFjU-8KWM
Neat, eh? As I was trying to load the video into YouTube I ran into a problem accessing the upload site. It seems Silverlight, Micro$oft's browser plug-in, was causing IE9 to freeze. I uninstalled it and I'm going to run the scenario again without it. Maybe that will help. I'll post my results here again.
More stuff to try! I'll get it one of these days...

Best,
Marc
EDIT: The Silverlight fix didn't work. I decided to delete the scenario and any of its copies from my TS installation and try to generate a completely new scenario, kinda like the others but just the basic trip from East Brunswick to Potomac. No AI trains. It's running perfectly. I guess there's SOMETHING in my work that's not behaving with TS. Temps are stable and no video breakup. I saved it mid-trip so I can go back to it, but I'm pretty confident it won't give me any problems.
Time for some refreshment...

M.