When I mark dimensions on 2D drawing, from time to time, I have difficult to mark them if one of the line/edge is centerline. Does anyone have similar problem? I am wandering is it a bug or there is any tips for dimension that I missed. The most frustrated part is I still can mark dimensions between centerline hours ago and suddently I can't any more.

Another question is sometimes when I try to show a detail view and found out the detail view is not the area within the circle. I am still not sure under what conditions this problem will show up, but it does show up a few times. It happens on both 2008 SP4 and 2009 SP2.