Similar thing happened to me.
But mine is stranger. First some one sent coins into my wallet and then they were taken out!! Has anyone experienced this before. Why would someone send bitcoins into someones account before stealing them?
You should open a new thread on this in future.
However, that was probably a bug in your blockchain.info account. Does it show the two trabaactioms of the mistake/theft? Or did the coins just go without anything in the history.
If it's in the history, make a new wallet on blockchain info and transfer all your coins there.
Those kind of transfer usually finds in the blockchain wallet when it is hacked only. Most of them would not be noticed the exact site while they logging into the wallet with the correct URL or not. That is the biggest problem for all the blockchain wallet users.
If you have VPN added while trying to login to the blockchain it takes you to different wallet and you should confirm your browser contains TOR or not. If he does not over cross the any of this issue. You will not get any problem.