From what I am reading unless you have a 2gb video card like a Quadro 4000 that thing will not run smooth. I realize you stated that your puters were 2500 which sounds like an starter mac BTW. The card alone is 700 for that.... Check your Video card and see how big it is. you can also change your render choices to help and use your CPU instead of your GPU for processsing.
Im uninstalling this software and counting my losses. Not a professional editing platform. After hours of searching online there are no available solutions. And MANY others are experiencing the exact same thing as I am and Ive tried on 3 Mac computers all recent models and the same result. All of my computers are at least $2500 a peice and have the maximum amount of ram available and its not enough. Last year I edited an event with Premiere Pro CS5.5 with no problems, and this year the same event I have to start editing again from scratch because I cant even open it in CS5.5. Im a die hard Adobe customer but this really does it form me in terms of CS6 im OFFICIALLY DONE. I cant even finish a 3hr project that Ive been working on its that bad. Definantly not recomending this to ANYBODY that puts any sort of value on there time.
Do you have any back ups of the project that won't open? Sometimes you can have better luck with them. If not, try starting a new one from scratch and then "importing" the problem one.
A lot of people are using Premiere and Mac successfully. Usually the more professional a user is the better they are able to keep there system up and tuned. One of the keys is having a dedicated edit system, getting any bugs ironed out then leaving it alone.
That's not to say that everything is rosy in Abobeland. The user forum is saturated with Mac users, which are a minority of users. One could expect an influx of questions from FCP refugees, but so many technical issues? One culprit most be the obvious overhead computing requirement to run Premiere efficiently. The lowballing of recommended system requirements listed in the adverts, courting Mac users whose macbooks and iMacs were not built for native HD editing have lead to a number of issues and disappointment.
And at the same time there seemed to be OS & software conflicts. Many Mac users were surprised that they experienced problems after upgrading their OS to Lion, even though CS 5 was designed for, and working on the previous operating system, and was released over a year before Lion.
I can't speak to your specific issue, but I wish you luck.
Message was edited by: Stephen_Spider because he can't form a cohesive sentence on the first couple of tries.