I'm getting the same widget problem as others have been reporting. It also seems to disable my 'tags' option on "EDIT | POST" and it's stopping another plugin ("Manual Related Posts") from searching and finding posts in the same menu.
Annoying, because it's a really great plugin ... and I'm determined to use it unless it blows my computer up! :-) Just have top deactivate it when I work back-end!
Another minor - but possibly urgent - point - I think you've got the syntax wrong on the "if function exists" text: kkLikeButton() should be wrapped in ticks ... 'kkLikeButton()' ... otherwise it doesn't work and you get a fatal error when you deactivate the plugin then view your site.
Sorry ... sounds like I'm complaining, doesn't it? I don't mean it to ... I think the plugin is absolutely fab! :-))
Am using it here ... or at least will be soon - I'm playing with it off-line first.