I had the problems of crash with arma2.
By Advanced Options video of arma2 I changed the parameter memory, by default to normal.
I use the resolution 3d and the interface 1280*720, now appears to be stable.
My pc:
motherboard: asus p6t deluxe v2 - 6Gb RAM
video: asus engtx285
windows 7 64 bit home premium