Just come it to my mind. is it possible? to get hook into your wallet and send some to another wallet? 
I don't know if you have seen but last months i have seen that many people were infected by a virus or malware which when people wanted to make a transaction the pasted address was always the hackers address so people were sending accidentally money to the hacker.
Well its the first time i see someone talking about some malware virus that affects the adress where we wanna to send the bitcoins,besides those i believe currently there is no way to hack bitcoin,since the hash protects the network.