Cubase 6 and Waldorf Attack problem

I have been using Waldorf Attack with Cubase 5.5. with no issues but now find if I run the Attack VSTI in cubase 6 on performing an action in cubase such as opening a window or menu or performing a mouse click the ASIO usage meter will go from just reading to full scale and the audio will become very distorted. Sometimes it takes a few seconds for this to occur, other times other times the applications will run ok for several minutes before it occurs.
Attack still runs fine on Cubase 5.5 which is still installed on the machine. Has anyone else experienced this? I am running on an Acer Laptop with windows 7 32 bit and using the generic low latency ASIO driver but experiments with other ASIO drivers have not cured the problem