Switching between applications is broken after some time

I am really at a loss here... Somehow my installation of KDE got corrupt, after I work for some time with my KDE Desktop, switching between applications using is broken and behaves really strange. When I press , the Application-Menu with "move", "resize", ... is shown instead of the dialog wi

KDE 3.1.3 Changelog - Trivia

As seen in the changelog for KDE 3.1.3: > konsole: Fixed fixed-width with proportional-font drawing routine. I tried to say "Fixed fixed-width with" 10 times in row, but couldn't. D.