If K9 Web Protection and Malwarebytes for Windows Premium are both installed on the same computer, you may encounter a blue screen referencing the error:
SYSTEM THREAD EXCEPTION NOT HANDLED (bckd.sys)
K9 Web Protection may conflict with Malwarebytes' Web Protection, causing a crash followed by the blue screen error above.
To prevent blue screen errors, uninstall K9 Web Protection from the computer or, if you have K9 Web Protection v4.4 or newer, disable Google SSL redirection. Disabling Google SSL may not prevent blue screen errors and may cause some websites to experience issues. For instructions, refer to K9 Web Protection's article How to configure K9's settings.