I cannot build projects with a strong name key signing - the message in the title always comes up.
Yes the project was initially copied over from another machine. Ho
It is not enough to manually add keys to the Windows certificate store. The certificate only contains the signed public key. You must also import the private key that is associated with the public key in the certificate. A .pfx file contains both public and private keys in a single file. That is what you need to import.