Isaac,
Check
www.knifeedge.com for the forum. I seam to recall some post concerning the USB ILink and specific G2 version numbers. I do not remember that actual version. I am running G2 with Interlink upgrade and version .570 without problem on a XP Corporate Edition O/S. I upgraded to .570 from .550.
Please check your version number in the Control Panel and update to .570 if you have an earlier version.
Also check the control choices to make sure you have selected the Interlink controller and are not still using the original controller setting.
Let me know if you are still having problems and I will gladly to a test install on another of my computers to help you out further.