When I try to view the solution log in the internal viewer nothing happens, what's wrong?

A. The internal viewer opens behind the main Sudoku window. If you run with the main window maximised, it's possible that you won't notice the log viewer behind it. You can either restore and resize the main window so that the log viewer is visible, or use Notepad to view the log. (Although one disadvantage of using Notepad is that it shows a static snapshot of the log, and is not updated as the puzzle is solved further.)