I just installed CS6 on a brand new 15" MacbookPro running system 10.9.3. Whenever I try to apply an unsharp mask, instead of opening the unsharp adjustment palette, the whole program freezes and I must restart the computer in order to get CS6 to run again.
Did you install all the updates for Photoshop CS6?
And if just Photoshop freezes, you should be able to force quit Photoshop and relaunch it - there is no need to restart the computer. Restarting the computer should only be required if the whole system freezes (which means a much bigger problem).
For me, this was just occurring even after reinstalling the PC version of Photoshop CS6. I could reliably "hang" Photoshop by opening a 20 megapixel picture, resizing it to 1000 x 1500, then using unsharp mask. A square icon replaced the mouse arrow and almost nothing would work. Menus would pull down but most actions I chose resulted in an irritating "ding." ESC wouldn't work, etc., but I couldn't get back my mouse pointer.