If you have a 3rd party driver, or HAL (Hardware Abstraction Layer). on a floppy disk, inserted in the floppy disk drive, and you 'press any key' to boot the Windows Server 2003 CD-ROM, pressing F6 allows you to load the floppy content, but when you press F6 again to load your other floppy, you receive:

The disk you supplied does not contain relevant support files. Press any key to continue.

To workaround this behavior, DO NOT insert any floppy disk until you press F6 and are prompted with:

Insert the Manufacturer Supplied Floppy.