Don't compare Blockchain.info. Bitcoins lost through Blockchain.info is very big and no, many of them were *not* due to users' faults.
if you are referring to the reusing of the "R values" by blockchain.info . i have to say, it could be easily avoided if the simple rule of "always use every address once" was followed, it could have been prevented.
i'm talking about a direct attack to your desktop, like a ddos, but with also the possibility for him to take control of your machine, i think not, but maybe i'm wrong
i have experienced a "TCP SYN Flood attack" which is a kind of DDoS attack. the attacker needs your IP to do this kind of attack AFAIK. besides i wasn't doing anything out of the ordinary.
i must add that the attack was simply blocked by my dear AntiVirus (Eset Smart Security) and i blocked the attacker's IP afterwards, just to be safe.