If you are seeing SD.Feeder.GeneralIncidentSubmitForm button in the forms list, it looks like a duplicate form has been published to the portal in the ServceDesk category of the Service Catalog.
Go to Admin > Service Catalog Settings > ServiceDesk, see SD.Feeder.GeneralIncidentSubmitForm listed in there, click the lightning bolt icon and choose Delete.
Second, when the form hangs blank when you try to open it, go to All Programs > Symantec > Workflow Designer > Tools > Log Viewer and see if there are any timeout errors or any other related errors thrown by the process. This would give an idea to what could be the cause.