I've seen that before, using untested drives. They'd work in one firmware revision, but fail in a later revision. Never could figure out why.
For what it's worth, I did notice that the list of tested HDs at http://serverconfigurator.intel.com/configure-ap.aspx?id=MTU3NCMx&ShowNavigation=false doesn't show *any* Barracuda 7200.11 drives, just the ES.2 drives. Might have to either stick with the older firmware, or move to tested drives, unfortunately.