Forum user "Mr Pippin" reports:
Haven't seen this, but since I've updated to the current version of iTunes, my player randomly will start playing music. Basically, if iTunes is running with no song playing, within a couple of hours, it will start playing the last song I was playing.Users should disable any third-party application add-ons or downloads they may have installed to determine if they are causing the issue. Users should also be sure they have the latest version of their current operating system. iTunes 9 is currently available for download from Apple's website and should fix this issue, though some users still report the problem using iTunes 9.0.1 and Mac OS X 10.6.1. Try downloading a fresh copy of the iTunes 9 installer (iTunes 9.0.1) and update your Mac.