Apparently, there is a hack of MyEtherWallet. The problem is spotted on DNS level. Do not login in MEW as your private key information can be compromised. Remember that you can always use public key and etherscan to check your balance.
Some updates on MEW issue.
MyEtherWallet is working fine and no issues has been spotted in its work. The problem was spotted on third-party level (DNS servers) which are the reason of security breach and private keys being stolen. It seems that third-party servers were targeted regionally, which means that only specific people from specific geographical areas were targeted.
I don't have any other information from independent sources at the moment, so take this information with the grain of salt.
Now, if you don't want to lose your money but you want to know your balance, use "See Balance Only". No need to use Private Key to check your balance. If somebody will get your public key - that's absolutely fine, as it won't give any access to your wallet.
Use your PRIVATE KEY only when you transfer tokens!!