Please try trashing the Preferences and check.
What is the best way to do that for encoder on the Mac?
Click on go option, selct go to folder and in the box type ~/library and click ok. In Library folder go to Preferences/Adobe/Adobe media encoder and rename the folder 7.0 to old7.0. Launch the product again and it will create a new Preference.
This may help if you are still working on this problem.
1. In the Finder, choose Go > Go To Folder
2. In the Go To Folder dialog, type ~/Library
3. Click Go
This will access hidden user library files in Mac OS 10.7 and 10.8