try taking the sound card out and restarting in safe mode. Then choose to show hidden devices in device manager. There might be soem references to the card(s) there which should be removed.
Shut down and restart in normal mode to make sure everything is OK.
Shut down and re-insert the cards, in different slots to be sure the OS thinks they're different and re-install the drivers manually if possible.
If this doesn't work you may have to manually remove the drivers (try c:\%windir%\inf) and go thru the process again.

hope this helps