After fighting for many hours, I finally figured out how to get WindowBlinds 11 working. I kept getting the -7 error, which means the certifications for WindowBlinds weren't installed for whatever reason.
If you have the same issue as I have and happen to stumble upon this post, just right click on WB11Config and go to Properties>Digital Signatures and with each certificate listed, click on Details>View Certificate>Install Certificate... and after all certifications installed, it'll now open.