RC2. Clicking on a link from the power lookup tool results as shown below. I can hover and get a popup or open the resource without problems from the book I am reading. Looks like it wants the old LLS file.
I reported this earlier. It particularly affects WBC and TDNT.
This will be fixed in 4.0b. (Beta testing should begin shortly after the holidays; there will be a brief rest for the... uh... wicked.)