Can you try removing XBMC to see if this cures your issue with ISO playback in MP?
James!
Already tried once (even if it was in reverse order, see below the steps made…)
I had the problem with ISO/IMG files not playing at all. I thought this problem occured since I installed Plex (from extras).
I then restored the aTV in iTunes to 4.4.4.
Did a new JB and a new installation of 1.2.
Before I installed any extras I tried to start two different ISOs. Unfortunately they both ended up locking the aTV with a black screen.
First time I waited more then 10 minutes, nothing else happened.
I unplugged power and tried with another ISO. Same sad result. Black screen and then nothing.
I unplugged power again and installed XBMC.
Did the setup in XBMC (had 3 crashes of XBMC before everything was set, a crash means get thrown out of XBMC and back to main menu to restart XBMC).
THEN I played the ISO with perfect smooth picture and no framedrops or lagging.
After this I tried again with playing the same ISO from mediaplayer. Sadly the screen turned black again.
As a clue for your troubleshooting: When starting the ISO-movie, it first seems OK, the “buffer-bar” in the bottom of the screen starts to fill, when it reaches 100% the screen turns black and nothing more happens. Still I can see that aTV is recieving signal from the remote (the led is flashing when I press a button).
Later today I can do another test to remove XBMC and play an ISO.
XBMC is still the only Extra I have installed.
Nope!
Tried uninstalling XBMC, but no difference to before.
Still Black screen when trying to play ISOs.
Now my only extra is the mediaplayer itself.
Pauem3
There must be a reason why XMBC plays Vob files smoothly but Mediaplayer doesnt :(
Must be something i Firecore’s software…
I hate the lag! And i hate XMBC because XMBC doesnt play all movies while Mediaplayer plays every .dvdmedia files i put in there!
I have just updated to 1.4. Even though the playback of ISO files has improved the issue is still present.
The stuttering playback of ISO, vob, TS type of movies will be improved with update 1.5.
I believe James said so in another thread.
Thanks Mikael.
Didn’t know that, because FireCore just closed the ticket I had opened without any further comments when they released 1.4. And the release notes did mention ISO playback improvement, so I got my hopes up and got a bit dissappointed.
Yep, a number of playback improvements are coming in version 1.5.
Hang in there. 
Sounds good!
Any ETA on the 1.5?
Most of the releases have been every 3 weeks. So given past performance I would expect the next release (1.5) to be in about 2 weeks time as the 1.4 release was last week.