The FXRuby CVS repository has moved from SourceForge.net to RubyForge. I don't believe that many people were actually taking advantage of CVS access, but if you were you should first do a CVS update of your local checkout and then identify which files (if any) are locally modified. After you do a fresh checkout of the code from RubyForge, just copy those modified files over and then blow away the old directory.

For more information about how to check out the source code, click on the "CVS" tab at the top of the FXRuby project page at RubyForge. The instructions in the FXRuby User's Guide are currently out of date and still refer to the SourceForge.net repository's CVSROOT, but this will be fixed soon.