The Premiere Pro CS5 (5.0.4) update (http://blogs.adobe.com/premiereprotraining/2011/06/adobe-premiere-pro-cs5-5-0-4-update-fix-for-crash-on-mac-computers-with-ati-cards.html) fixes the problem of crashing on Mac computers with ATI cards.

Premiere Pro CS5.5 doesn't have the problem.