I am having a problem shutting down my computer. After I go to "start" & "shut-down", it starts to shut down normally,but it just stays busy on the screen where it looks as if it has a haze over it. Also recently some programs are "freezing-up", and not letting me do anything. To get out of them i have to hit Ctrl+alt+dlt, and "end task". What do i need to do to fix it?