Hello Kent,
With the update to 1.5.15 of joomla! some mistakes has slipped in.
Strange enough, I have also upgraded to 1.5.15 and no problems whatsoever.
At the backend its not possible to see the listet testimonials and the other two editable things (sorry I have it in german so I don't know the english titels for them)
Did something change with your database maybe? Can you see if the jos_jdtestimonials_ tables are still there?
At frontend there are now 2 funktion.reset tags on the top of the page:
Is this part of JD Testimonials? Sounds like something else.