This is an odd one. If there truely is a service running that is blocking this: you can try 2 things.
***Before trying these unistall the audio drivers. First unistall out of the add/remove programs from the control panel. Then go to the device manager (Right click on My Computer, click manage, Then go to Device Manager) Right click on any/all the audio drivers and unistall.
1. Tap 'F8' continuously before windows boots to run in safe mode. This allows only limited services to run. Try installing in safe mode.
2. Right click on My Computer, Click Manage. Click on Services and Applications, then Services. Stop any service that could be related to audio. Try reinstalling.
Good luck!!!