Having run into this myself, I found that doing a quick /status to get the offending user's client number helpful. Then just /clientkick # (where # is their client number) and viola, they're gone.
Originally posted by [KWA]SaVAgE
I got people doing the good old colored names and thats fine, but, when I go to kick a llama and the Llama has colored letters, i can type in there name PERFECTLY and it says player not found.
This is via RCON while I'm playing BTW.