Bluetooth Dongle + Bluetooth Headset (Plantronics M3000) = urgent sound quality! HELP!

hi,
i want to use my bluetooth headset plantronics m3000 with a bluetooth dongle
(yakumo; widcomm software 1.4.3.4), but the sound quality is more than bad.
i hear interference sounds 2 times per seconds and the output is retared.
what can i do? i've searched for three hours in the internet by now and i've
found nothing. please HELP!!!
thx!
tim