I messed up the Java that came with Fedora linux and had JAVA_HOME pointing to Sun's JDK. Then I downloaded Ant, set ANT_HOME to this new location and whenever I typed ant i got an error message :
Unknown argument: -cp
Even though when I did a "which ant" it pointed to the correct location which was in ANT_HOME/bin/
Googling did not give me any useful results. Then I thought am I the only one having this problem - so I tried in yahoo ( was planning on trying dark lord's search if it didnt work) - and got the first result with the solution itself. You can try this search query "ant unknown argument: -cp" to see how Yahoo trumps Google in this. Google if you are reading this clean up your act.
Anyways heres the solution. Remove the ant that came with fedora.
Become root and type : "yum remove ant"