i recently installed xp pro sp3 onto my unibody macbook pro but theres no sound! yes, i have put in my leopard disk to install boot camp drivers but still no luck. system sounds are not played, the speakers arent even recognized and external speakers dont work also. when i press F10,11,or 12 it shows the muted sound symbol with a crossed out circle on the bottom. keys for screen brightness and backlighting work fine. when i go to volume control it says 'there are no active mixer devices available. to install mixer devices, go to control panel..etc.' i tried this and it doesnt work also theres a unknown PCI device with a yellow explanation mark next to it and i tried installing drivers for it, says some kind of error. code (or error) 28. i also tried installing realtek (or something like that) drivers but those dont seem to work i have googled this for solutions but none seem to work help plz!