Issue with SQL 2005 Backup: Error message when you perform a full backup of a database in SQL Server 2005: "Backup failed for Server 'ComputerName\SQLInstanceName' " or "The backup of the file or filegroup 'sysft_FullTextCatalog' is not permitted because it is not online"
1) Put the database into single user mode.
2) Start to detach the database. But before clicking OK for the detach, UNCHECK the box that says "Keep..." (the rest of the line is not immediately visible... what it says is, Keep fulltext catalogs. Get rid of that). Now OK the detach.
3) Reattach the database, and the backup works. Just like that.
Good luck everyone!