This happens to me every time. It usually occurs roughly 3-4 minutes into starting the simulation. Yoke/throttles/etc all lock up and result in crashing. If I start the sim, walk away for a few minutes and come back (while its sitting engines idle), same freeze occurs. When I close out FSX from flying the B737, I get a Windows exception error. Never had anything quite like this with any other payware, so its an odd issue.