That is weird. Do you remember the options you gave the installer? Can you reproduce this problem on a fresh install with those same options (the installer probably created a racket-uninstall script)? If the installer created them (try which racket), do the /usr/bin ones work? I really don't know what's up. I'm still running mzscheme v4.2.1, so I'm not sure if/why Racket would create all those binaries with the old names, either -- mzscheme, drscheme, etc.
