Sn45G spdif(optical) out problems

i've now had my box for 2 months and in the last few weeks my onboard sound doesn't work. When i boot to XP i dont see the nforce drivers under system and i've also noticed that the when i boot the optical out light comes on for a few seconds and then turns off.
some times the sound will come back after restarting windows...im really at my wits end with this should i call it a day on the onboard sound(which i love on my logitech z-680's) and buy an audigy...any help will be appreciated..........

Sn45g
Barton 2800+
TwinMOS 512 3700
Powercolor 9800 pro
SeaGate 120GB

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