Yesterday after I upgraded my alu iMac to 10.5.8, my Bluetooth mouse wasn't registering. When I went into System Preferences, and when I checked my mouse settings, I was told that a "Bluetooth module was not found". How can I fix that?
Reset the PRAM and see if bluetooth is still malfunctioning. The other thing to try that worked for me in the past, when I used to have the occasional problem, is to reboot into Windows, and then reboot back into OS X. My bluetooth would mysteriously start working again.