Is the constraint engine completely broken in 2010?

I am having nothing but trouble with the constraint system in 2010, constantly getting the error message

"This relation could not be added because i6t would cause invalid geometry in the sketch"

This on things that absolutely should work.  Equal length relations (yes, they are in the same sketch and in the same plane), collinear relations.

This very difficult to work around and I'm having to add hundreds of extra dimesions because these relations are failing.

SolidworksSketching