Hey mate,
Not sure if this is still a problem for you but I’ve got 2 potential fixes for freezing on your mac.
a) do a clean intall, directly duplicating the disk from one drive to another will not get you the bet speeds. For mac I’d ay the best way would be to do a time machine backup (or another incremental backup program) then do a fresh install of your latest version of OSX and restore the data/apps you need from that
b) someone further down mentioned Nvidia issues… that should only be a problem if you have incompatible RAM for sharing with the Video card… I grabbed some generic DDR3 ram for my MBP and it would crash as soon as the Nvidia card was used for anything 3D but would work fine for the desktop so long as the Intel video card was being used
