LightUp v3.0i
The new owners of SketchUp, Trimble, have been cleaning up the way in which SketchUp registers with Windows. All good, but it was breaking the LightUp Installer detection of where you have SketchUp installed..
New installers now available which should resolve the issue along with a fix for not repeatedly popping up a dialog asking you to setup Anti-aliasing.
Grab it from the Downloads page