However, doing so causes a slowdown. You will get the spinning rainbow cursor when any system-wide authentication window, even the login window, prompts you for your password. This is very bad, as if you are someone like me, get this authentication prompt about 10 times a day, on average.
After much frustration, I searched Google. I couldn't find anything. I search a second and third time, a few months later, nothing. I finally decided to search once more, and found an answer! I wanted to post it here, so it's easier to find the answer for anyone else who may be searching.
René's fix was to change the owner of specific files, but I find it much easier to delete the /Library/Caches folder and reboot. It's too bad repair permissions can't fix these cache files as well. I know this happens on 10.4 and 10.3, but I'm not sure about 10.2.

