I have purchased CS6 and I am having problems with the 64-bit version. After I open it completely freezes and I have to force close it. This happens every time I open it. I have tried uninstalling and re-installing it multiples times. I didn't have this issue with CS5. I am running this on a Mac 10.6.8, Processsor 2.8 with 8GB memory.
If you're on a Mac, there is only a 64-bit binary.
You need to troubleshoot your system. I'm running it on a MacBook laptop with just 2 GB of RAM (more RAM is on the way) and so far it hasn't frozen or crashed yet.
Have you tried to reset preferences? This file not affected by a re-install. Mac believe you start PS and IMMEDIATELY hold down the cmd + option + shift keys. Should get a reset window.
Not a mac guy but I read about Apple Disk Repair? that is run to fix things.