I just found this article regarding the Ethereum network and how it may be possible to disrupt the network continually via Smart Contract Unfortunately this does not look good.
Quote:
If the malicious contract has a high enough balance in Ether, it is possible to run iterations on such a contract indefinitely. Doing so would slow down the Ethereum network and effectively bring to a halt. With US$1m of Ether, one could halt the network for 2 days. Increase that number to US$50m – an amount some nefarious entities may be willing to part with – and Ethereum could be reduced to an obscure project in a month or less. It is only a matter of time until all hell breaks loose, that much is evident.
Have a read and continue doing your own research on this matter.