From what we can tell there's a uncommon condition on the network (seems to be about 1 in 10 clients), where some databases have became corrupt. Please check your logs for these messages:
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2015-02-15 17:34:26 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large OR 2015-02-15 17:34:26 ERROR: ReadBlockFromDisk : Errors in block header
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If you find entries like that delete ~/.darkcoin/blocks and chainstate, then resync from the bootstrap: