I dunno why Solidworks and me don't get on. I'm doing a 3D sketch. It's all fine, fully defined apart from the bit I'm working on. I draw a line between two points and the sketch becomes over defined. How or why? The line has no relations, it's just a line being added between two points. The sketch is fine before the line is added, and over defined once I add it. This has happened several times now :/

Here's a short video, 30 seconds:

Line over defines 3D sketch in Solidworks - YouTube