Nuendo 6 32 bit issues with powercore vss3,recording etc

I’ve recently updated my system from nuendo 4 to nuendo 6.I have hp xw6200 xeon 3.2 Ghz(2 processors)-5 Gb ram-win 7 64 bit. Rme madi system with yamaha dm 2000 mixer and a pci powercore with vss3.
I’ve downloaded all recent drivers but my nuendo doesn’t seem to run properly. The vss3 vst plug is listenable only with nuendo 6 64 bit version (I’ve installed both 32 bit and 64 bit).With nuendo 32 I can see the plugin but the sound is not listenable.
Another crazy issue is that at the time I press the record button sometimes the cursor runs and it seems to record but when I press stop the wave sound is not completed!!!
I load 2-3 sounds with kontakt 5 and my vst performance is horrible.I can hear cracks and sometimes it sounds as it jumps the tempo…etc. even though the bar at the vst performance is not low.
I’ve almost regretted for this update.
Before with nuendo 4 I could load more vst insert(waves compressors etc) and many vst instruments with not so many issues but now it is impossible.
Also when I zoom in or zoom out I hear some noise.I’m thinking about my video card (nvidia quadro fx 540)or the nuendo 6 has more requirements…I can’t think anything else

Have the same issues with Powercore on N6. No sound…