Hello Dave Parrish,
This issue comes from installing the SIT patch on a computer that has already had the patch installed. For example, installng SIT 1.0 and the patch, uninstalling SIT 1.0 and then reinstalling SIT 1.0 and then trying to reinstall the patch.
To resolve this issue, delete the following two (2) items from the C:\SimulationInterfaceToolkit\ModelInterface directory before reinstalling the patch:
nidll_vc.sav
VILauncher2.exe
Regards,
Chad Evans