A small fork has been detected on the network. It is actively being corrected. Please check your Sterlingcoin wallet's block height against that of either explorer:
https://chainz.cryptoid.info/slg/ or
http://transactions.sterlingcoin.org , they are both correct.
If you find your block height does not match that of the explorers, recent snapshots are available on the website and under the 'Download' navigation.
Sorry for any inconvience.
My wallet happened to be on that fork, so I downloaded a snapshot from "Recent Snapshots" -> "Windows/Mac (Berkeley DB 6.1)" link from the "Downloads" section of the sterlingcoin.org. However it seems to be more than 230 days old. Will it help to switch to the right fork? I am not sure the fork is that old...