also the apple dvd player does not play burned dvd's. which is kinda funny that you cant watch an idvd you made on the computer after you made it, thats how I found out it doesn't work.
You could try VLC, thats what i use to play my burnt dvd's
I have a 2004 Powerbook 15" and if I turn audio off via cntrl/F3 then suddenly DVD's wont mount to the desktop... soon as I turn speakers back on viola...DVD's mount again... very strange but maybe it's supposed to do this???
I dunno but anyway if this is your problem try my quick fix...