final cut pro freeze frame not workin

In addition to Tom's advice, another way to reset FCP preferences is to hold the option and command keys when you launch FCP by clicking it in the Dock. A dialog will appear confirming you want to delete the preferences. Choose Delete Preferences. FCP will reset its preferences, put a diagnostics file on the desktop which you can safely move to the Trash, then it will open the default Untitled library. Reopen the library you were working on, set the preferences back to the way you like them (disable background rendering, reset Import to Leave Files in Place, etc.) and see if the issue has been resolved.