Jim, I see that changing your avatar got rid of the Photobucket message that was showing in lieu of your profile picture. I would try something similar with respect to your signature showing the Photobucket message. Try going into your account and completely deleting your signature; then replacing it with a new signature using only text. Hopefully this will remove the Photobucket message.

Finally, although it's not an ideal solution, you can always go into preferences and choose to not display signatures.