p5n32-sli SE coax output doesnt work in Vista x64 (software

I've struggled with this for a while.. and now i think ive narrowed
down the problem...

With the Asus P5N32-sli se onboard Realtek audio.. it will not output
dolby digital via the SPDIF via software players like PowerDVD,
Windows Media Player etc on x64 Vista...

On this same x64 Vista.. I can goto control panel.. audio.. playback
devices.. the digital audio one.. properties and send Dolby test
signals fine and clear to the receiver.

But on the same x64 Vista, if i attempt to use PowerDVD (set to output
over spdif).. it will freeze up.. I also tried WinDVD, it wouldnt
freeze, but no audio was heard.. With Media Player it didnt output any
sound Via spdif...

I'm at a loss on x64.. as i tried x86 briefly.. the sound coming from
PowerDVD did output Dolby Digital...

Anyone happen to have this board.. and has found a way to get Dolby
over spdif under x64 vista?

I'm guessing its a limitation of the software under x64, not the
hardware or the realtek drivers?

Thanks in advance..