BTW what sort of a graphics card do you use? If it is a built in on the motherboard you are recommended to actually change to a graphics card, even a dirt cheap one, the hiccup that is created when the graphics core momentarily takes over control from the memory controller can interrupt the timing on Cubase and Nuendo.
P.S. Like your username, I still use the old 01W for AM sounds that no softsynth appears to offer properly.