Illegal memory access after resetting to the sample zero

[sasmaster]

I was trying to make demuxer running in loop. So that when it has reached the last sample it resets to the start of the track and keeps running. When I fetch sample = 0 into MP4D_frame_offset() it crushes at when it tries to read the 'size' at some illegal memory location.
I was trying to find where in your code you increment buffer pointers but couldn't find any. Would be nice to get an idea what could be possibly wrong.
Thanks.