I like having the grid visible for guides during a project, but almost every time I go into Utilities>Options>Grid & Ruler Spacing, and try to enter values (e.g., Major Spacing 1 foot, # of Subdivisions 48, or most other inch-based entries tried)I get Warning msge, telling me "The grid spacing entered was invalid, must be a positive, non-zero measurement" etc. But the values I'm trying to enter ARE positive, non-zero measurements! This is driving me nutbags. Any ideas? Thanks in advance!