system hanging up while relinking media on opening a project in productions

I've found that my projects will regularly hang up while relinking media after launching a project in a productions project.   When I open a project I always watch my progress window now to watch the media relinking on launch.  The relinking for each project will either be completed rapidly and the launch is successful, or the relinking will hang at 99%, and sit there, and i know that project will crash pretty soon, so I have to shut down the project, reset my preferences (which means slowly going through and resetting all my. preferences again), and try my luck again.  It's a 50 / 50 chance of haing projects open up without hanging up.

This seems to be connected to the fact that i have to continually re-link the same proxy media files each time I open the various projects within my production (this is despite rebuilding my media cache & resetting my app preferences)

I'm currenlty on beta 26 build 50