Middle-mouse-button (to move the screen) does not work anymore It seems my MMB is completely broken in Blender (only in Blender) because not even combinations with this button worked. It worked fine just a week ago, but since i have downloaded 2.76 this problem occurred, even when i switched back to 2.75. I don't know if the download of 2.76 was the impact because i didn't use Blender 2 days before i have updated it.

How can i solve this problem?
Do you use Photoshop Elements in parallel to Blender? I once ran into such a problem and it is a known issue of PE that the right mouse kind of redirected. For me, it helped to stop PE.