It sounds like you've made a permanent alias [maybe you aliased ls to ls --color ] Check your ~.tcshrc file
Did you install a colored ls before? if so either remove the alias or reinstall ls color [http://macosx.forked.net].
I mentioned the colored ls thing, because that's what happened to me. colored ls was installed in /usr/local/bin and because apple went and changed $PATH on us, the colored ls wasnt found. ls was taking --color as the first argument and then interpreting -l as the directory. Confused me at first, but I figured it out