Grrr since this just came up in another thread, I realized this was missing here:
Check to see if what you are experiencing seems a repeat of bug #206888.
https://avid.secure.force.com/pkb/ar...-ins-on-launch
And if this happens get at least the Pro Tools log file... and lets see if it gives and clue. They are not overwritten each time you start Pro Tools so should still be there.