I have motherboard DN2800MT (board model, BIOS version, Chipset driver version in attached images) with Windows XP Professional SP3 and external USB Audio soundcard.
Soundcard is USB 1.1 device with external power supply.
When I connect soundcard to any of 4 Rear panel USB ports all is fine. All mixers (playback and record) are active ("active mixer.PNG"). But when I connect soundcard to any of 4 Front panel USB ports (directly to the headers on motherboard) some mixer lines are inactive ("inactive mixer.PNG").