1. We always suggest that customers run the latest version if possible. You can see a list of all the changes that have occurred since 1.7.3 here:
http://www.activemodules.com/active...e-history/ 2. Make sure that your Sign-Up view has permission to be viewed by Registered Users and Also Unauthenticated Users. Also make sure you are using Public or Verified registration (Admin > Site Settings > Advanced Settings)
3. I do not know what the discount would have been for, it is possible it was only a temporary discount. You would need to find the original email for more information.