I have a similar issue.  Computer freezes after varying amounts of time.  With Malwarebytes uninstalled I can use the computer normally. Windows 7 x64 Pro up to date. Malwarebytes Version up to date. No BSOD, no memory dump.  SFC clear, memory tested OK.  Mainboard drivers up to date. This started occuring 23rd December.  I've been away since 14th December so I can only assume an update was released whilst I was away and installed on my return which has caused this