in ACA 2010 I am now unable to place a modelspace view on a sheet file, using navigator. When I attempt to do so it gives me the universal no sign, the circle with an angled line through it. I have tried it in multiple projects, multiple sheets, new and existing, and on multiple computers. It is possible to do it by xrefing the view into the model space of the sheet file and cutting a new view port into it. This is something that just started today, it had been working previously. Any suggestions would be greatly appreciated, I currently have some very frustrated users and an equally frustrated CAD manager.