Crashes started a few days ago here, too. Graphics freeze requiring ctrl-alt-del to bring up task manager and close proggy.
Windows 7 64Bit Pro, ATI 4670, on-board sound, no swap file, clean install, dedicated HDD, default services.
It started happening the day I subscribed, so I assumed it was the downloading of plane skins that was doing it. Turning that feature off didn't correct it.
The game crashed about 10 times this weekend after never having done so before.