Occasionally, I will be using the computer and surfing the web when the internet will cut out. I know it is working b/c other computers can still get to it. Then, I try to open another app, and they will bounce forever and not open. Then, when I go to shut down, it will never get off the background screen. I have to force it to shut off by holding the power button. I have tried the usual repair of permissions but it doesn't seem to help. Any suggestions. I am running 10.4.2 on a 15" Powerbook.