If you primarily use your MacBook with an external monitor, and prefer to disable the internal display when it’s connected, you may already be aware of the terminal command which allows you to turn off the internal display whilst it’s connected to an external monitor (dimming the screen doesn’t count):
Now, when you start up (or wake from a sleep of more than ~30 seconds), with the clamshell closed, only the external display will be used, even when you subsequently open the lid.
However, if for whatever reason, the internal display becomes reënabled, then going through the process again of putting MacBook to sleep, waiting, then waking it (making sure the lid is closed) can be a pain. Instead, try this: Close the lid (with the external display connected), open
System Preferences), and rotate the screen 180 degrees. As long as the lid is closed, then when you cancel this (either by waiting 15 seconds, pressing the
Return key, or standing on your head and clicking the
Revert button), the internal display will again be disabled.
Incidentally, to put all displays into standby mode from the terminal (without putting MacBook to sleep), use
Also, if you have an external USB hub which occasionally causes a connected keyboard or mouse to pause every few seconds, try changing the screen resolution. This should offer a temporary respite (but I assume it’s a hub incompatibility).