bad Knights download causes problems
 

Something went wrong when I tried to download Knights; some files could not be downloaded, if I understood correctly. Whatever happened is now causing strange errors: some of my fonts in Firefox have changed, and I cannot copy and files to the desktop. I tried copying a file there (no relation to the Knights download), and it said, "Could not start process io-slave: klauncher said: Error loading 'kio-file'." Also in Konqueror, some of the letters in the status bar at the bottom have become highlighted in red blocks. I'm going to get rid of Knights and try a different chess front-end.

You might want to check (or recheck) the installation instructions for clues.
http://knights.sourceforge.net/install.php