Lately I have been having problems with my 3-4 year old iBook, running OS 10.4. Many programs, including the Finder, freeze up and sometimes even Force Quitting doesn't do the trick. I have to hold the power button to restart it. It then works good for awhile but then I have these problems again. Does anyone know what I could do to solve these problems? This computer is no longer in warranty (it expired last fall), so I'd hate to pay big bucks to get it fixed at the Apple store. Thanks.