I had this problem also flying the Tutorial flight from VRMM. It occured on two flights roughly in the same place while cruising at 4x speed.
Again I tried it today after downloading SP1b it froze once more but this time I ignored it and left it frozen, about 10 mins later it continued flying as if nothing had happened. It froze again after about 15 mins again I left it and it unfroze after which I achieved a fully autolanding at Dubai. It was wonderful. I'm not sure if SP1b had anything to do with this as previously I have always exited the program. The Vas meter never went above 3 Gb in my settup and occasionaly it was below 2Gb. No doubt there will be a perminent fix for this problem shortly.
Gradon