Hello Kiebach,
I don't know which version of TestStand you are using, but this is not a standard TestStand error, it indicates an ActiveX communication problem. Does this problem occur when you run the original simple LabVIEW operator interface and shut it down? If so, then there might be a corrupted installation, so uninstall/reinstall.
If this does not occur in the original simple LabVIEW OI, then keep in mind that the biggest culprit in ActiveX errors with LabVIEW is not closing all of your references. Be sure to check on that everywhere you have added features.
David Mc.
NI Applications Engineer