I was also unable to complete any renders to .mp4 of AVCHD files, was getting crashing at completely various random places. Then I tried the CFF explorer hack that is mentioned with this issue and after making the changes to vegas100.exe IT WORKED. Completed render!!
Was ony a 1.5minute clip as a test but never made it over 55% previously, so to complete is good sign. Not sure how long of a project can be rendered as RAM usage went over 4gigs (I have 8).
Will keep testing on longer clips. How is it possible that Sony can not/does not fix this!!
This is in regards to Magic Bullet Looks applied to events, mostly fine without MBL, still the odd crash with the Sony AVC render but Main Concept seems to work and that's with 32bit Floating point, 2 pass 8Mb/s etc.