it happened to me recently when installing a CW card in a friend's PC :
Scope had been isntalled with no problems. the scope window appeared when openinf scope. everything were ok except the fact that the dsp load window did not mention any usage (zero % !) ; furthermore Nuendo said that the soundcard was not "open". In fact, although it was possible to put wires in the rooting window, change sample rate and so forth..., scope was not openned. This problem occured several times and sometimes not. Any idea?