When I sent payment,there was debug messages as follow and my wallet became "not synchronzied ".  After I restarted the wallet client the error is the same and I cannot synchronize. Then I restart both bitcoin-qt and msc wallet client, it's ok. 

DEBUG: Sanity checking balances table...
BLOCKSCAN: Finished, sleeping.
DEBUG: Thread exited.
DEBUG: Thread 'workthread' starting...
STATUS: Connection to bitcoin RPC established & sanity check OK.
STATUS: Connection to database established & sanity check OK.
STATUS: Database starting at block 289322
STATUS: Network is at block 289327
STATUS: 5 blocks to catch up
DEBUG: Block Analysis for: 289322
DEBUG: Block Analysis for: 289323
DEBUG: Block Analysis for: 289324
DEBUG: Block Analysis for: 289325
DEBUG: Block Analysis for: 289326
DEBUG: Block Analysis for: 289327
BLOCKSCAN: Found MSC transaction (accept offer): 485aecab6cf60af5cf2e50fa6fea71226e2efa1c091e084e33ce1bfc7a8e5a09
DEBUG: Block Analysis for pending transactions
BLOCKSCAN: Found pending MSC transaction (simple send): 37372d20fd5cd5bfa98b0a53072e775d333eaa55c960ec63c8117a7732cfbefa
BLOCKSCAN: Transaction processing starting...
DEBUG: Enumerating addresses...
ERROR: Blockchain scanning thread threw exception : 添加或减去的值产生无法表示的（my translation : "The added or subtracted value results in an un-representable"） DateTime。
参数名（my translation "parameter name"): value
DEBUG: Thread exited with error condition.