ronenmiz - I thought I would reply to your post as I found this thread whilst trying to resolve this problem myself and found that so far there is no official resolution.
I reside in the UK, unfortunately I cannot tell you the model number or purchase date of the XBox as I bought it second hand, however I can tell you that the xbox is running the latest available firmware in my country, and the TVersity Server version I was using was 1.9.7 . Additionaly I can inform you that my experience of this problem did not occur after an upgrade or reinstall - it just started to happen one day when I turned the XBox on. As far as I can tell, there were no hardware or software changes on the Server machine at the time the error started occurring.
The problem does happen with ALL video files. Infact when you enter TVersity from the XBox video viewer, all of the usual folders (All, Dates, Folders etc) show up with the 'no entry' sign, and bizarrely when you click on them they behave like media files and open up the 'play, resume' dialog on the XBox (rather than allowing you to browse further into the folder hierarchy). Clicking 'play' does absolutely nothing.
I can confirm that re-scanning the media library does not fix this problem, but completely uninstalling TVersity and reinstalling the same version DOES fix the problem for me.
I have [literally] just purchased a license for version 2.2 so I will re-post here if I get the same problem again at any point. If you have any more questions, feel free to drop them below, also I will see if I can extract the exact model number of the XBox from within the firmware if this will still be of benefit to you.