Sluggish mouse at near 100% cpu usage with 7600gt????

Hi, some weeks ago I swapped my old Athlon 64 3200 for a x2 4200 (both 939), and my x1600 for a 7600GT. And since the very moment I installed the nvidia drivers the mouse cursor got sluggish when the cpu usage is high.

I REALLY don´t know why this happen. I´ve make a clean install, and still happens (not in VGA mode, just once I´ve installed the drivers). I tryed the old x1600 in the same windows installation and everything works perfectly, but not with the 7600gt.

Why???

Does it have something to do with high pci xpress use in this card or what?

Which is even stranger is the fact mouse controlled games (i.e. comand and conquer 3) doesn´t show any sluggerish at all in the cursor.

Also the behaviour doesn´t seem to affect linux or Osx86 (didn´t try Vista).

Any suggestion?