WASD movement key problems

Sometimes the WASD movement keys don't work.
When I press A to go left, my toon goes right.
Sometimes when I press any of the WASD, my toon just stands there and I have to rely on the mouse.
I'm using Java 7 with Ender UI
When I press A to go left, my toon goes right.
Sometimes when I press any of the WASD, my toon just stands there and I have to rely on the mouse.
I'm using Java 7 with Ender UI