Trouble in dropping a table: not there but appears in systables

I have a database that I can't save the structure of (with dbschema) as there's a weird table in it and dbschema falls over when it comes to it. I can't drop it as it says it doesn't exist. I can't modify it as it says its not there. Yet it appears in systables. I can't delete from systables where tabname = table's name as it says no permission. How can I get rid of it? Kate