Character moves slightly while crouching?

I have a character which I have a few scripts in, the one I'm having the problem with is the heavily modified ThirdPersonController script, converted into C# (my preferred language) and converted to first person. I have added a crouching functionality which works almost perfectly.

The problem with the crouching mechanism is when I press the crouch key, my character jumps slightly in the last direction it was moving in, even if it is still when the crouch key is pressed.

I have a theory to why this might be happening:

• The script might store the previous direction then apply it when the CharacterController leaves the ground (due to crouching).

The reason I want the character to leave the ground is because I wan the functionality of crouch-jumping to be in my project.

My Modified ThirdPersonController script (now FirstPersonController): http://pastebin.com/QLiXmv6E

Crouch-Jumping: http://www.giantbomb.com/crouch-jump/3015-1492/