I used to only have to shut down my computer every month or so but now I have a worse problem. Whenever i start my computer, everything works fine. Programs dont lag, everything is copied quickly, no high fan, no unusually high memory usage and extremly smooth performance. But after a few hours, 2-5 my I can't save anything. When i press save and choose the file name or when i click "Open File" in the menu bar the application freezes. Then i have to force quit it, and then i can't open it again. Then the same happens to every application, they all freeze and I can't do anything so I have to force quit them but then i can't open them again. Whenever i shut down my computer, it just freezes. So I always have to force shut the computer down. What is my problem? I have repair my disk I have repaired permissions I have Reset NVRAM I have Reset SMC I have Deleted all Cache.