I've been scratchin' my head over this one, but we've been gettin' this error everytime a user tries to export via excel. We've tried everything, and at this point we are at a loss. When the user clicks on a table/chart/etc. to export to excel, it gets to the point where the user gets prompted to "open the excel" or save the excel, but it's at this point we get this error:
Hope that someone can help out.