It's your IO subsystem, without a shadow of a doubt.

Errors are moving around because the IO subsystem is corrupting different parts of the various files.

You need to move off that IO subsystem until you figure out what is wrong with it. Use SQLIOSim to diagnose - see http://support.microsoft.com/kb/231619 - IO subsystem diagnostics are usually not sufficient to stress the IO subsystem into producing errors.

Thanks