I had this problem.
It happened when I adjusted the screen resolution in the nVidia driver to the lowest value (800 X 600) then adjusted it back to native (1280 X 800). It was a fix in Steinberg Cubase 5: To get the transport bar in view when using non HD resolutions/monitors.
Anyways, after doing the above I realised that it was my monitor not adjusting correctly to the video signal. (I have a dual monitor set up and the screen on the right was fine. So I swapped the monitors around, electrically!, and the same monitor now on the left, still wasn't viewing right. So it wasn't the GPU card.) Doing the above resolution switch cured it. Its a funny fix to a problem but I put it down to the ageing TFT driver circuits in one of my monitors.
Not saying you have to do the same but just letting you know that it could be your monitor thats the fault as it was with me.