In Live Forms v5.0 if you publish a custom control it creates a bad entry in the frevvo FormMetaDdataType database table. Users will notice the problem when they view the production forms list and click on the form name link. You will see an error message "The requested application was not found".
When you upgrade your Live Forms server you will need to run a database script to remove these bad entries. Please contact customer support for assistance.
These issues were recorded in tickets #12415 and #10895.