It looks like Thinks.com has changed the URL format for their daily puzzle. If you use the Thinks.com source, you should open it in Preferences and change the URL to:
Unfortunately if you've already tried to download for today, Black Ink will repeatedly try to open the "Bad Puzzle". So you'll want to locate the bad puzzle file and delete it:
[Home] -> Library -> Application Support -> Black Ink -> Puzzles -> Thinks.com Daily
Then retry with the new URL in place, and everything should work again!
Hmm - I'm confused. Now that I look more carefully it seems that what probably happened is you had existing MacXword preferences on your computer, and those preferences had an outdated URL for Thinks.com.
There might be other "out of date" URLs in your Puzzle Sources, so it might be a good idea to delete both the "com.advenio.MacXword" prefs and the "com.red-sweater.BlackInk" prefs and start from scratch.
In the next update to Black Ink I'm going to add some smarts to the app so it will update existing sources that have the same name as built-in sources, putting the latest URL in place of any existing one.