I have my 15" MbP for 1&1/2yrs(its my first mac), got 2g ram and was delighted with the speed when new. But it got slower and slower over time and now is at the point where i want to kill it. Start up take 5-15mins, apps take minutes to open and frequently crash. Even if i'm just on the web(with no other open apps) clicking a link or switch tabs freezes and spinny-wheel appears(sometimes for minutes). I've done all the maintenance things I know about, tried many things. Is it normal for a machine to deteriorate this much over time? What can I do to restore my mac to its former glory?