Check for media file, project or prefs corruption.
I know I'm going to sound like an idiot but how do you check for media file, project or prefs corruption?
Hold option down while launching to reset prefs.
Start or open another project with different media. If everything OK, that makes it look like your project or media are corrupt. Start new project with same media. If OK, then your previous project could have been corrupt. And so on.
Deleting your media cache can also banish some crashing.