Jeff,
anytime you have less than 5% space left on any drive, this disk will not be reliable.
Try a couple of these:
– export to another drive
– export non-self contained and ‘consolidate’ using compressor
– trash your render files and re-render your whole sequence in one run. Your problem might be caused by a corrupt clip or render file.
5.0.4 has been good to us so far, but looking forward to 5.1 for numerous reasons (separate timecode capture, 5.1 audio, 720p25 integration, more intelligent nesting, advanced attributes-handling, advanced speed-menu’s etc.etc.etc.)