Draw Wire tool snaps to drawing origin

When I start to draw a wire in Promis-e the Draw Wire tool will snap to the origin point rather than where I click.

If I right click to cancel the operation, when I left click to start drawing a wire again it will snap to the position of the previous right click. If I change tools, then reselect the Draw Wire tool it snaps to the origin again.

This happens in all projects.

I've probably altered a setting without realising exactly what it would effect. Can someone suggest how to stop this?