When I try to draw a line, I left click on the start of the line, but before I can click on the end of the line, a short line as drawn starting from the left click position. What can be done to correct this?
You may be using the wrong tool. In LibreCAD, the behaviour you've described sounds like the Angled Line, Horizontal Line, or Vertical Line tool. Instead, you want to use the "Line by 2 points" tool.