My cousin's 2.0 GHz 20" Core Duo iMac (the first Intel one, if I'm not mistaken) constantly needs its PMU reset in order to make Bluetooth and the internal IR receiver work. I turn it on sometimes and bluetooth is there and the remote works. Other times the bluetooth icon disappears and the remote doesn't function. To get it to work again, I have to turn the iMac off, unplug it for 30 seconds, and when I boot up it works again. (these are Apple's PMU reset instructions.) The machine originally had 10.3, was upgraded to 10.4 who knows when, and just got upgraded to 10.5.6 via install DVD and then combo update to 10.5.8. Unfortunately I think it still does it on my external USB hard drive, which is a 100% fresh install of 10.5 upgraded to 10.5.8. Is there an internal battery that could be dead (like the BIOS backup on a non-Mac)?