I'm not a techie as I have said before, but OOM has to do with vitual address space. Here is somewhat of an explanation.

http://janvaane.org/virtualfsx/?p=927

Again, I suggest the hardware forum at AVSIM or SIMFORUMS. These guys are the best source of help. Here's a thread from the AVSIM W7 forum on OOM.

http://forum.avsim.net/topic/360114-oom-with-high-end-system/page__p__2294284__hl__oom__fromsearch__1#entry2294284