This thread is for future help for Apple Aperture 2 users and missing or corrupt Export Presets settings. I searched the web for a solution and there were a few people with the problem but I found not solutions. This way if someone comes here looking for the solution they may find it and save themselves from having to completely remove Aperture and reinstalling it (which by the way will not work).
The answer is pretty simple; just go to your Hard Drive > Current User > Library > Application Support > Aperture and trash Export Presets.plist and restart Aperture and Aperture will create another default plist. The same goes for PrintPresets and MetadataSets. Custom data will of course be gone as well - but it's better than a re-install.