YOU didnt really do anything most likely, (unless you are solo mining with alot of hashpower heehee), its more likely that through all the updates ESP has had one of your connections may be outdated and you (by chance) got pulled onto its fork when you got a block from it. this is normal in coins like this, and not to be alarmed! delete everything, BUT YOUR WALLET.DAT file, and sync again, make sure only official nodes are in your config!