Just thought i'd post since none of the above suggestions did didly squat for me and I finally figured out how to kill the damn Gamejack virtual parasite.
Reinstall the software (painful I know)
Find the Gamejack directory (normally program files/Gamejack 5)
Right click unidrv.msi and select "uninstall"
Painless and simple
Iâ€™ve tried hacking my registry to bits, deleting sys files from my Windows folder, uninstalls like the previous posters described. None of them WORKED AT ALL.