Using the Swing wallet, twice in the last few days my blockchain db has become corrupted.  I fixed it the first time by deleting the files and redownloading the blockchain but now it's happened again.  Why is this happening all of a sudden?  It was working well for a month and nothing on my end has changed.

-02-08 00:24:57 Opening LevelDB in C:\Users\Admin\AppData\Roaming\Zclassic\blocks\index
2018-02-08 00:24:57 Opened LevelDB successfully
2018-02-08 00:24:57 Opening LevelDB in C:\Users\Admin\AppData\Roaming\Zclassic\chainstate
2018-02-08 00:24:57 Opened LevelDB successfully
2018-02-08 00:25:03 ERROR: CheckProofOfWork(): hash doesn't match nBits
2018-02-08 00:25:03 ERROR: LoadBlockIndex(): CheckProofOfWork failed: CBlockIndex(pprev=0x13650c10, nHeight=260687, merkle=e4d8c3a173e8f65e216a6c2981f3e9b74c2e9ac7097d06106cb544bc594b209e, hashBlock=1e20be214a25945cbbb8eee162f09eccdd66400a3192775ac64dff32dd2fccc9)
2018-02-08 00:25:03 : Error loading block database.