first roubleshooting step is to repair permissions using the Disk Repair utility that came as part of the OS installation...
I've been using Safari ever since I bought my MacBook. It was perfect because it did everything I needed from a web browser, had a nifty little search box, intergrated excellently with the OS and Mail, and did RSS!
Then I opened Activity Monitor... the program was using 500MB of RAM after ramping up about an hour of usage. While I am a very heavy user (50 RSS feeds open, YouTube, CNET, CNET TV, Crave, web based email etc...) I was astonished to find this to be the case.
So, I moved around for a while. I'm a poor student so OmniWeb was impossible. Firefox isn't so great because it is a port. IE was a joke. Camino!
Almost. Camino has no RSS reader. This is a big negative for me, so I grudgingly went back to Safari and the spinning beach ball of death. One particularly nast day (iTunes downloading, Messenger chatting, Safari in all its glory, Mail, QS, and so on...) and the Mac freezes up. I leave it to detangle itself for 15 minutes and decide to move to Camino and Google Reader. Perfect.

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