Take a look at this article - Seems like your issue - can you do the workaround?

http://support.microsoft.com/default.aspx?scid=kb;en-us;827448&Product=sql2k

I know that someone said to reinstall SQL, which is a bit drastic but may need to be done but have you tried just rebooting the server? Maybe start here?

By any chance, do you have a table named the same thing as your stored proc? I have received the error message when I try to create an object such...