Did you solve this issue? The exact same thing happened to me on a macpro (trashcan) and i had to do a clean install of OSX only loading Adobe and other apps that i needed for edit, etc. This was after trying all the fixes stated here and having a tech go thru my system. The clean install fixed the problem, but it is back. It happened when i used Digital Rebellion Preference Housekeeper to remove caches and prefs. Anyone out there with any insight or ideas? Thx