SQL Server 2005 database corruption. Advise
As you have an old backup with the correct schema, the problem database is online and you've successfully queried several tables, I'd be inclined to try get a dump of the raw data as fast as possible.


Shut down the applications accessing the database.
BCP export the data, table by table to files. As disk corruption could be the source of your woes, export the data to a portable drive or to a fileshare on another machine.
Restore your old backup to a known good server.
Depending on the complexity of the database schema either truncate the data from your restored backup or script out the schema and create a new empty database.
BCP the data back in.


The data may contain inaccuracies, it may be missing rows or contain spurious values. But with any luck you'll end up with more than was in the month old backup.