Does relaunching litestep.exe (via task manager) help? If so it might be a problem in the startup code. Are you sure that it's rundll32.dll? You may also want to upgrade to the latest LS build. Run C:\Litestep\Utilities\UpdateBuild.exe and point it at http://leaf.terica.net/software/releases/lscore/LS-0.24.7-RC2.zip