"SyntaxError: Unable to parse JSON string." Stuck in updating mode...? Help!

I'm trying to edit an unpublished Instructable, and get an Instructable  "parsererror." "SyntaxError:Unable to parse JSON string." 
The Instructable is saved under my "unpublished" tab, but I can't edit it without getting this error, and then get stuck in "updating" mode.
I had a problem adding comments to a photo, and wonder if this might have something to do with this error? 

Suggestions?