[Brimmy]

I have recently upgraded fom PT 5.0.1 to 5.1.The system is a PTMIX system running on a Mac G4.Since the upgade I have had a number of problems opening sessions from the older version. This however is not consistent and some sessions open sometimes but not others.When trying to load a 5.0.1 session everything appears to be OK -the session boots up the DAE,locates and appears to load the audio files,the Pro tools menus appear at the top of the screen,then it suddenly crashes.When I check to see which programmes are still running ,the DAE is there but not Pro Tools.When I try to restart however I am told that the DAE is still being used.The session I really need(and have not been able to open at all) to be able to open is quite large(1.5gig) and I have tried copying it onto different drives but this has not solved the problem.Individual audio files from the session can be imported into 5.1 sessions but I really need to open the whole session.Any ideas please?