I bought a 15" powerbook two months ago. First, the battery died. Then really odd things started.Sometimes when I used limewire, my computer kicks itself off line and I can not scroll as fast. I have to restart my computer. i tunes will get stuck on a note, making a echo like skipping sound, then it just stops. I reinstall OS X. I ran the hardware test. I haven't reinstall limewire, and I have a new battery. Yet all of the problems perist. Over all things just don't run as smoothly as on my 12" powerbook. What can I do?