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:
--
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
---
If you find entries like that delete ~/.darkcoin/blocks and chainstate, then resync from the bootstrap:
https://github.com/UdjinM6/darkcoin-bootstrap
Thanks 
i had those two days ago .. they must have caused my MN to stop working back then. I remember someone else complaining about these errors back then .. i did a reindex then
and had no problems anymore.
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Deserialize or I/O error - ReadCompactSize() : size too large
2015-02-13 22:33:07 ERROR: CheckProofOfWork() : nBits below minimum work
2015-02-13 22:33:07 ERROR: ReadBlockFromDisk : Errors in block header
2015-02-13 23:02:08
Yup - I had that too.
A -reindex did not help, only a full resync with deleted blocks/chainstate (or a bootstrap resync)