Server is running with pure on, it means that your quake3 has to be pure non-modified as well
probably one of original q3 files were modified, those are packs pak0-8, if you downloaded any of them from external source makes sure to use proper ones, also you can additiobaly delete/move all the aditional pk3 from baseq3 just to make sure everything is ok, delete all the zzz- name starting paks.