I have a new (2013) 27" i7 Imac and installed Win7 Pro using Bootcamp. The Windows sound was fine until I installed the Nvidea drivers for the 380M sound card. I also installed Nvidea Audio drivers, and now there is no sound. I have tried everything, including uninstalling all the Nvidea software. A techie says Nvidea may have written something to the Windows BIOS, but I know of no way to check the BIOS or make changes. Any suggestions?