Well the ATI card (5770) takes the whole system into a lockdown when attempting to switch any attributes of display (res, refresh). By default it runs at 1920x1440 at 85Hz which is too high for most 3D apps and games. Forums and the web are full of similar stories on all kinds of systems and ATI cards so it must be the Win7 and ATI driver. I've tried 3 driver versions now all have the same problem and I guess people on LCD screens (majority of users these days) never switch resolution or refresh hence don't report the problen. Did I really need DX11 hardware, wish I would have gone for the Nvidia 260 now.