Hi All,
I've also met this kind of problem /ArmA crashed after 2 min playing/. Although it occured for me under windows xp with 2Gb memory. I never tried under windows vista.
People who have a lot of memory think that they do not need windows swap mechanism or they set the size of the swap file manualy. I though that 1Gb swap and 2Gb physical memory would be enough for my system for everything. But I'm wrong In my case ArmA crashed about 2 minutes playing. It gave me no error message just closed.
So I think you should check first wheter your swap file's size is limited or not. The best option is to let windows handle this automaticaly.
Hope, it will help some of you Sorry for my poor english.