Plex stopped playing MKV files

Plex works great on AppleTV2.

 

All my MKV files play fine, but after awhile it stops playing them for no reason whilst AVI’s still are fine??

 

Last time this happened I restored my appletv2 again and then rejailbroke it and installed everything from scratch and it was all working fine again, till today.

Removing and reinstalling Plex doesnt work?

 

It seems to play up after installing other plug-ins from the management tab.

 

Also, when going into preferences for plugins like apple movie trailers the preferences dont show up, but they did before this Beta 5 update?

 

Any ideas?

 

Thanks