I seem to have developed a   Tolerance problem. Two weeks ago I did some work on 2012 Autocad and  I know I did change a setting.  Now when I draw a rectangle the diagonal is not straight. The diagonal line joins the vertices( osnaps) but the line appears slightly staggerd. Its possible that the rectangle vertices are not truly aligned and could be off by a few thousands. I detect this problem  even the on solids, the diagonal slicing planes are not quite diagonal but offset to the edge by a minute value.  It was ok  two weeks ago. I cannot remember what setting I changed. The straight lines are good in ortho and polar . Can some one help