Lose your laptop? Change all passwords, pronto   Elie Bursztein,
left, highlights Windows password vulnerabilities during a Black
Hat talk. Elie Bursztein, left, highlights Windows password
vulnerabilities during a Black Hat talk. Declan McCullagh/CNET
LAS VEGAS--If your Windows laptop is stolen, be warned: new
research shows how a thief can gain access to the passwords used
by your Amazon.com, Google, Yahoo, Facebook, and other Web
accounts.  The passwords for accounts in the cloud are supposed
to be protected by Windows' built-in encryption. But a team of
security researchers demonstrated at the Black Hat security
conference here how last week to bypass the operating system's
security.  A thief--or someone unconcerned with the finer points
of federal hacking laws--can take advantage of the vulnerability
to discover the passwords stored by Web browsers and other
programs like instant messaging clients. So can police using
electronic forensics to analyze a computer seized during a
criminal investigation or w