On a newly created 1.7.2 Multiplayer game, with 3 regular players, 1 player cannot manipulate any blocks in what appears to be a full chunk. The 2 other players can work this chunk as normal. Affected player has no problems outside this chunk.

Restarting both server, and clients have not fixed issue. It looks a lot like severe lag on affected client, the block breaks, then pops back. But only in affected chunk.

No exceptions reported on client or server logs.