This sounds like something has gotten into a bad state--perhaps a process that's hung. Have you rebooted the system since this started happening?
If not, then before trying that, I recommend closing AME and the program(s) that you're using with it [Premiere Pro, After Effects, Flash, ...], and then checking Activity Monitor for any processes that remain behind after about 20-30 seconds. The main ones to look for are:
- Adobe Media Encoder
- Adobe QT32 Server
If any of these is still shown in Activity Monitor a minute after closing the last Adobe app, use the Force Quit command to kill it. Then relaunch AME, clear everything from the queue, reimport your files, and see whether you can change export settings.
OK, so I think I've figured something out. There is one particular format
of video that seems to be screwing things up - Apple XD Cam EX.
It seems that just having adding that to the queue screwed up something - I
tried a different file format after restarting my computer again and it's
On Fri, Mar 16, 2012 at 12:04 PM, Benjamin Hecht