I'm running the OpenSky 747SP on FS9; model is the OS747SPV4A_SOFIA observatory bird. All panel switches, aircraft animations, etc function as advertised. Following a normal engine start, takeoff and climbout at about the 50 minute - one hour mark the sim quits abruptly with a CTD. This has happened twice this evening. I am running GameBooster v.3.0 on my machine. This situation occurs whether GB is running or not. Only other thing running in the background is Avast virus protection for the machine. I can not figure out what may be causing this as GB shuts off all ancillary functions in the machine, which in theory should keep this from happening. Is there something corrupted in the aircraft model or a conflict with some basic FS9 function?