It doesn't require a 64-bit OS. In fact, people running 64-bit OSes are having the problem as much if not more severely. For me, this started after 1.6 on a system with Win8 64-bit and 16 GB RAM.
Oh I didn't know that
I'm going to upgrade to WIn 7 64Bit and hope I can play at least more than 2 hours at a time (as a dps you are in the queue for that long sometimes....)
It started with 1.4 for me and every mini-patch it just got worse. At first I crashed like once every six hours, then F2P patch made it really bad and I crash every 1-2 hours.