'Nother problem

[JustinMeyers]

now when i put the disc in, an error message pops up that says
CRC error the file c:\program files\sega\medievalII total war\packs\data3...some other stuff, doesnt match the files in setups .cab file the medium from which you are running the setup may be corrupted;contact your software vendor.
plz help

[sapi]

Try giving you disc a quick clean - a CRC error usually indicates a problem with dust/scratches

[ShellShock]

Also see this.

Watch the long links, mate ~sapi