Yes, the problem sounds even more difficult than I thought--you have my sympathy.
AC seems to be doing everything that it can to figure out a very rare and very hard-to-reproduce bug.
Given how hard it seems to be to reproduce the crashes on AC's hardware, I keep thinking of crude tests available only to users on their own hardware, such as swapping in a different video card to try to rule out obscure video driver and hardware problems.
Another thing that I don't remember anyone mentioning is whether AC crashes when run just on the local server itself, which might rule out any weird network hardware and configuration issues.
