Vista - Vista blue screens when i try to play audio

I have just built my first pc and installed vista home premium, but every
time i try to play any audio, after a few seconds vista freezes (blue
screens).
When the pc comes back on it says that the nvidia nforce4 audio driver needs
updating. So i downloaded the latest driver off the nvidia website, but when
i try to install it it says that the driver is allready installed.
Smoebody in another discussion group told me to try and roll back the
driver, but when i do that option and button is greyed out.
can anybody help me please.