Found this on their web site. " After a long beta development period, we've activated our Shuriken heuristics module in today's definitions (version 4390+). Under the Settings -> Scanner Settings tab in Malwarebytes' Anti-Malware, check "Enable advanced heuristics engine (Heuristics.Shuriken)" to enable this feature." http://forums.malwarebytes.org/index.php?s=d29fac7c317052c7028921c813755adc&showtopic=59510