I was fooling around with TNT and the area revert function and discovered that if you blow up a large area and revert it all at once, the reverted chunks start to crash players' clients. No errors in console to the best of my knowledge. It fixed itself between 15 minutes and 3 hours after the revert.

To replicate: Place 64 TNT in a large grief revert field. (we used something like 300x50x300 (xyz)) Blow them up. Revert and your client should crash. Anyone who tries to load those chunks should crash.

Fixed in 5.5