I got my replacement Fujitsu MAM3184MP disk yesterday. Transferred my filesystem over, and sent back the dying one today. All FedEx 2 day prepaid. Best disk RMA experience ever.
I got my copy of Civ 4 today. There's no crack yet. So first it wouldn't start because Disc 2 is incorrectly labeled the "Play" disc. Disc 1 (the "Install" disc) must be inserted to pass copy protection. After that, it displays some loading bars and crashes. I was all set to blame the copy protection, but the game apparently does not play on ATI Radeon cards.
There is some kind of hack that I haven't tried yet. But seriously, what the hell Firaxis?