I have had this issue in the past. I have 2 suggestions for you.
First, delete the preferences. My favorite tool to manage preferences is:
https://www.digitalrebellion.com/blog/posts/preference_manager_2.0.1_released.html
The next option may simply be to reinstall compressor. It is actually pretty easy, and this link will help.
https://www.digitalrebellion.com/blog/posts/how_to_reinstall_compressor_and_qmaster.html