If you are 100% sure that is not a hardware problem within the wheel, the only suggestion is to uninstall the software for the wheel completely, go to safe mode, check there are no instances of the game within the registry or use Ccleaner to clean the registry.
Check for an update version of the wheel's software and install it again.
Could it be that Windows 7 added Generic drivers and all you need to do is update its drivers? perhaps you should check this first before you do the uninstall?
Sorry, shots in the air here as I have never used a wheel before.