I think it was an internal problem in blockchain server. Seems to be solved now. My wallet seems to be fine now, but i am still going to buy a cold storage device now. Any ideas for a good device?
you don't need a device for that..
Basically a good Paper Wallet is the best thing you can use as a safe paper wallet.
https://www.cryptocoinsnews.com/tutorial-create-bitcoin-paper-wallet/But Blockchain.info safe to use. Just back up the Wallet data on a USB stick / Print out a back-up on paper.
Blockchain.info just never has access to your wallet, they just store your wallet file which is opened in your browser not on their website. That's what most people don't know.