I'm currently working with a rather large MythTV recorded file (1.8GB MPEG) with AVS Video Editor 6.0 and getting this same error.
Before the error occurs, I'm watching one of the CPU cores running at 100%, and memory usage shooting up to fill the system memory, at which point Video Editor seems to come to a halt for a while, then the memory usage plumets down and shortly after, the exception appears.
I've on occasion been able to catch errors that seem to refer to NULL addresses (0x00000000), but reproducing these are random and tricky, perhaps when the system runs out of memory to allocate, you're missing some checks to if the allocation succeeded or not.
From editing itself, the memory usage doesn't start to rise rapidly until the clip is actually on the storyboard. Able to import the clip into the library, trim it, but the moment it gets dragged to the story board, CPU and memory usage go nuts until memory fills, at which point the "External Exception EEFFACE" box pops up after a short period of time (reliabily so, able to reproduce at least the EEFACE box on demand).
The file I'm using is a MPEG container with 3 streams (1 video, 1 audio, 1 subtitle). VLC reports the streams with:
Video:
Original ID: 512
Codec: MPEG-1/2 Video (mpgv)
Resolution: 720x576
Frame rate: 50
Audio:
Original ID: 650
Codec: MPEG Audio Layer 1/2/3 (mpga)
Channels: Stereo
Sample rate: 48000 Hz
Bitrate: 256 kb/s
Subtitle:
Original ID: 576
Codec: Teletext (telx)