Ok, i think i solved this problem.(Fingers crossed)
You have to turn on DEP (Data Execution Prevention) in Control Panel/System/Advanced/Performance/DEP Prevention/
Turn it on for all programs, no exclusions.
After that , reboot your system.
I did this and guess what , i let DCS World run for at least 30 minutes without getting the BEX64 error.Before this , the game crashed in single player after say 5 minutes.
I hope it will help for all of you experiencing this problem.
I will test this furtheron.I'll report back on it if i discover more problems.