There's an irritating (if not especially serious) bug in the HD graphics control panel:
A few weeks ago, I noticed that my laptop screen had started changing brightness depending upon what it was showing. It was particularly obvious because I work simultaneously in Visual Studio (white background) and Sublime Text (black background) and constantly switching between them made the 'ticking' of the brightness very apparent and distracting.
I searched online for a solution and tracked it down to the HD graphics control panel, "display power saving technology" option.
Only problem is, that option wasn't there, so there was no way of turning it off.
After some head-scratching I discovered that the display power saving technology option is only shown for 'on battery' usage. Toggling it had no effect because the laptop was plugged in.
Fortunately, there is a workaround: if I yank out the power cable, the control panel switches to battery mode and turns OFF power saving. I can then plug the laptop back in and it will keep the 'off' setting.
This happens every few days, despite the fact that I have NEVER turned on display power saving. Every time I have to pull the plug and replace it to get the control panel to respect my settings. I haven't been able to track down the exact sequence that triggers the bug, although I think it might be removing the power cable while the laptop is shutting down.