DVR recordings aren't being moved out of .grab

I’ve attached a screen shot to illustrate the problem. Every now and then for some reason my plex DVR recordings don’t get processed after completing. They end up piling up in the .grab directory. If I restart Plex, it deletes all the pending recordings in the .grab. I don’t have any custom scripts setup to post-process recordings, and I have on-the-fly transcoding enabled.

Screen shot of problem:

After a bit more digging, it looks like the recording never happened since the .grab directory is mostly empty. Something must have gotten messed up with the recording in the background

[Jun 26 07:09 ajs@rhea:/mnt/raid/data/dvr/tv/.grab]$ du -h
4.0K ./ebd2c71063cd519037edf74c493cc428714fd578
4.0K ./3114d29d3fdf56700cd1816a27d2395128220d35
4.0K ./959b6dd110ff5b9c71207f67ab986d0c952f831c
844M ./f7083f36bbfa7e7df1eab9d2344a98346ec3d038
69M ./7f7d2867f8dfa85209d5f7f95a06d457bf9ec471
4.0K ./8fa8bcff70be5078db8841a4b12f9322e652648d
4.0K ./c8a0d8d17cd448e13830f150350220a45059ae2f
912M .

Looks like this is a dupe of http://forums.plex.tv/discussion/274585/issue-with-tuners-and-recordings