Hey,
I am having the same problem. Sharing from MacBook to an ATV2. It was working for probably about a month before this started happening. When I select the first movie to play, nothing happens. The clicking "select" noise is made, but the screen doesn't change, freeze, or anything. If I select another movie to play after that, a window pops up that says "playback failed, one or more items failed to play. Check log for details."
here is the log from my ATV2:
http://www.xbmclogs.com/show.php?id=8266
here is the log from a Mac Mini I borrowed to test it:
http://www.xbmclogs.com/show.php?id=8267
Things I tried:
upgrading, downgrading, nightly builds, monthly builds, changing network protocol (Fails on both smb and afp), different file formats, (mp4, mkv, and mov all fail) I tried other systems (installed XBMC for mac on a mac mini I borrowed and it did the same thing. I also completely uninstalled and reinstalled XBMC, and also re-jailbroke my ATV2. No cigar.
I recently upgraded my MacBook to Mt. Lion. And, if memory serves, it seems as though it worked for a while after I upgraded to Mountain lion, but it was soon after that it stopped working. It seems that my macbook server is the culprit, but I just don't understand how, as XBMC can access and see all the files on the server, just not play them. And I tried Plex as well, to see if it was a server issue, and it worked just fine. I just like XBMC so much better, so Im hoping we can find a solution.
I deeply apologize if this problem has already been addressed. I googled and searched these forums and this is the only thread I could find with any promise.
Thanks so much for any help you can provide, and please od let me know if any more information is needed.
Nate