This week has been a pretty interesting week for me so far because I'm training a new guy on InfoPath 2007 and InfoPath Forms Services and we are getting new errors and I wanted to share one of them.  "There has been an error while loading the form" was an error that we got today when launching one of his forms.

After doing a little investigation we discovered it was a old form that he deployed and activated to a Site Collection through InfoPath Forms Services but then decided to remove it from InfoPath Forms Services before deactivating it from the Site Collection.  I was pretty amazed that he was able to successfully remove the form before deactivating all instances.  When I looked for the deployment files in the Features folder they weren't there so it appears it was removed successfully.  To resolve the problem we delete the form entry from the Form Template library on the main site and deleted it from the Site Content Type gallery.

Cheers