At the moment many Ethereum owners see that Exchanges disabled deposit/withdraw on their websites. That's because ETH network reached it's transaction limit - I think at least.
I don't know but it seems that the ICO launches and/or smart contract/transaction spamming makes the network pending transactions. At the moment ~11500 txs pending according to https://etherscan.io/txsPending ... and it's counting. The main reason is maybe that ETH network is still has old "internal components".
This is one of the first times when ETH network shows it's dark side but I think it is not the last time we see situations like this. Still everybody should calm down, because if you start transactions you may lose money and just making the situation worse...
A hint according to Lefteris Karapetsas on twitter
"Hint: For those waiting for their ETH to get burned in the contract, cancel it by making a plain value transfer with 51 GWEI." "You would still lose ETH but less, since it would be a succesfull simple value transfer with huge gas price."
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