Bitstamp is blaming it on malware...I'm using my office laptop which has no dodgy software on it and has Symantec running.
Clearly...bitstamp is to blame for my loss.
Symantec is worst anti-virus dude and no anti-virus can keep your pc safe.
Also are you sure that no one else except you accessed that laptop or your email id? Possibly someone that knows you personally did this.
I will advice you to install malware bytes anti malware and scan your pc. If you have downloaded anything recently scan it on virustotal.com and btw do you have Java enabled in your pc?