Seems Avast is also causing a BSOD on my machines too...
Clicked the green popup today (25th Dec) on my Windows 7 RC desktop machine and when it restarted I got a BSOD with just the RC windows build notice in the corner (Ctr, Alt, Del didnt work) after hard restart and starting in safemode, I stopped Avast from loading next time the machine started using msconfig and the machine starts fine.
Also noticed the same problem on my Media Machine running Windows 7 Home Premium, turned that on this morning and this evening only just realised its been sitting with a BSOD all day, this time it gives , same safemode, msconfig to remove avast from startup and it restarts no problems. But can't remember if/when i did the latest Avast program update on this machine.
So far my netbook running Windows 7 Home Premium and Avast seem to be unaffected.