I'm downloading the blockchain from scratch, and it's been stuck at 2442432 for a couple of hours now.
The chain structure keeps on downloading though. Is there a way to find out how much of that is left before the blocks continue?
I experienced a similar issue while testing a clean local install of Mist Wallet and Ethereum.
This is very likely the result of the large amount of spam-generated state from the recent attacks (which is displayed as "chain structure" in the Mist splash screen).
"You're not stuck in a loop; the attacker created a lot of state. It'll finish eventually, and the forthcoming second fork [EIP158 State Clearing HardFork] will reduce the state a lot." - Nick Johnson