There may be a partial/temporary solution offered here

The final Yellow flag was harder to trackdown, and may be the one identified by gehanna. When you look at it's properties, it has a Hardware ID of ACPI/PNPB006. It turns out that it is the NVIDIA(R) nForce(TM) MIDI UART. Whilst I believe that one option is to turn this off in the BIOS, I hate admitting defeat like this. I was actually able to install the driver from the old Windows XP 6.86 nForce AMD package I had on the HDD where I keep all of my old drivers. I pointed the Install Driver dialogue at the AudioDrv subdirectory of the previously used driver package here. (i'm sure that NVIDIA will update this part of their Vista Driver soon. They seem to be working on a lot right now!