Perhaps you're using TOR? I've never had this problem before, but maybe Blockchain.info is now trying to prevent people from using their service for illegal purchases/services?
If this problem persists, I suggest you either:
1. Use a VPN if you really really like blockchain.info and will die without it
2. Use another online wallet like coinbase, or use bitcoin core.
Not using proxy, not using tor, not using a vpn. I am not a spammer or hacker or anything like that. I did e-mail them backasking why I was banned in the first place but they did not reply . I am however fully unblocked now but it is strange I was blocked to begin with.
Just in case something happens like this in the future, and you need urgent access to your coins, I recommend exporting your private keys and importing them to a Encrypted desktop wallet like Electrum or MultiBit HD for save keeping. You never know - They could ban your IP again or get shut down for whatever reason or they might get DDoSed, which would remove access from your BlockChain.info wallet.