Go to the waccom site for your specific tablet, there should be instructions for this.
What I had to do was pull out the plug then uninstall everything, then restart and reinstall everything with the plug back in. It fixed it but I think one of my antivirus scans killed something so I might need to reinstall the drivers again :/
Trust me, once you get this fixed its a lot more manageable and youll be a lot more sane!