I have had an issue where elements in section, elevation, or detail windows appear on my monitor to be in one location, but when attempting to select anything in these windows one finds that the expected nodes are not where they should be. This is a bit difficult to explain so bear with me and attempted screen captures don't get a useful illustration.
This "bug" is periodic and going to other views and returning to the problematic view will often clear up the issue. This just happened again this morning in a detail window. I tried to select a fill by a corner node and no snap point (check mark) were at any of the corners. If I move my cursor around I would find the node and get pre-selection highlight about 5 inches below where the element is displayed on my screen. This actually seemed to be a pixel distance since at different zooms this distance varied. This could be seen be relocating the user origin to this node and zooming in or out. In essence the element appears to be displaying in the wrong location on the monitor.
Could this be graphic card related? I have an ATI Radeon 9650 card in the computer in question. Have any others run across these strange display issues? I have seen this both in AC 10 and AC 11.