Invalid host bit mask Sysprogs forums › Forums › VisualDDK/VirtualKD discussion › Invalid host bit mask This topic has 0 replies, 1 voice, and was last updated 12 years, 3 months ago by gr4g4e. Log In Register Lost Password Viewing 1 post (of 1 total) Author Posts September 15, 2012 at 06:17 #529 gr4g4eParticipant I have an error when i start the virtualbox: Failed to open a session for the virtual machine windowsbox. Invalid host bit mask. (VERR_PDM_INVALID_DEVICE_GUEST_BITS). And how to register? Author Posts Log In Register Lost Password Viewing 1 post (of 1 total) You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In