Read this, it would indicate a metadate error

http://www.sqlservercentral.com/articles/Corruption/65804/

this article links to this

http://www.sqlskills.com/BLOGS/PAUL/post/TechEd-Demo-Using-the-SQL-2005-Dedicated-Admin-Connection-to-fix-Msg-8992-corrupt-system-tables.aspx

Paul Randal is the man. He wrote DBCC CHECKDB, I would treat whatever he says as gold.