I’m also having the same problem on a MBP running 10.6.8, I can confirm the game does run it just takes often many attempts to launch the program. After logging in and clicking Play, the message comes up “Exception: c0000005
A serious error has occurred that prevented the application from continuing. A report has been sent to ArenaNet to help determine the cause.”
It is still possible to play I just have to start the program enough times :S. It’s strange that the client worked perfectly the day the mac beta launched, this only happened the next day.