From the error you've provided, it appears that the computer you're trying to use doesn't have a microphone that supports Proximity or the computer is causing interference. Have you tried to turn off any microphone enhancements etc, as they can cause issues with Windows based computers.
Note, Proximity has it's own section in the forums: Cisco Proximity, where you can get specific help regarding this product. You can move your question to the correct section by editing it and changing the categories at the bottom.
