i had the same problem i solved it by working on it all day here it is go to this site and download the driver for windows vista to fix the problem
http://support.asus.com/download/download
-item.aspx?model=a8n-sli+se&product=1&type=drivers&slanguage=en-us
this is the site the file you need is Beta driver for device PNPB006/MIDI 511.2535.0 put on you desktop and the go to device manager and up date the driver with this one error gone
hope this helps you from extreament RemoveThis @msn.com