I was mixing a session last night and then all of a sudden my session was nothing but static, so I closed the session restarted the pc and went to open the session up and got an error message saying protools can't open the session because it was created with an earlier version. I am using 7.4 i think not at the studio so can't verify but it's either 7.3 or 7.4. From my experience you can open earlier versions of protools sessions with the current protools. Mind you like I said I was in the middle of mixing the session already and it was recorded with the same version of protools. This is why I'm stumped.