Horrid microphone buzz on Win 2008

[Nick_C]

I seem to have a problem with my microphone on my Gigabyte GA-890FXA-UD5 running Windows Server 2008 R2.

This machine works fine running 2003 but with 2008 R2 installed the microphone just buzzes so much that it is completely unusable. Win2k8 has correctly detected the 'High Definition Audio Device'. I have even tried the Gigabyte Realtek Azalia driver but still the same.

Any ideas what I can do to cure this.

Edit:
I have now traced this down to the Hyper-V role, with that installed the buzzing starts. Still don't know how to solve it though.

[Nick_C]

Narrowed it down a bit further; only occurs when the hyper-V role is installed in Win Server 2008 R2. Uninstall Hyper-V role and audio recording again works fine.