Have you been receiving a "Session timeout" error message while trying to buy something from iTunes? Well, here's the odd (and easy) answer to that particular problem: your system clock isn't synchronized with Apple's! Although this is reported as a Windows problem, some Mac users are also experiencing this problem. Click on the title link above for the solution given by PCWorld. Or, if you want the Mac solution right now, open "Date & Time" in System Preferences, make sure that the box for "Set date & time automatically" is checked, and in the panel on the right select "Apple Americas/U.S. (time.apple.com)". Oh, and don't forget to set the correct time zone: Phoenix - U.S.A.
Thanks to the Prescott Computing Society Newsletter for this tidbit.