Hi need help about my speakers

hi when i install windows 7 ultimate im having problem with my speakers

i have logitech g51 surround speakers

when im playing music i think only 1 speaker is working ?

and when i open my creative soundblaster X-FI B a error pop out
it says


the current selected audio device is not supported by the application ...
then when i select another audio " high def audio device" it says the same thing..

what do i miss???