We were forced to migrate to a new server on Saturday, September 27, 2014. This change makes it impossible to register or update older versions of PartyCAD 12. CDs prior to version 12.2.360 should be destroyed as they no longer allow for registration or updating.
All is not lost. Your serial number is still good and will work with the latest version of PartyCAD, so all you need to do is install/reinstall PartyCAD from the online version and you will be back in business.
To install / reinstall:
If you have problems, see here for more complete instructions.
If you need to install PartyCAD on an offline machine, see here