Microsoft disclosed a new bug in Windows 10 that causes Desktop Windows Manager (DWM) to crash when a laptop lid is repeatedly opened and closed.
The problem affects only laptops running at 4K resolution either natively or via an external monitor. Microsoft says the problem stems from the DirectX Video Memory Management component and is not a hardware issue. As such, the bug, which was first reported by Bleeping Computer, is expected to be resolved through an upcoming software update.
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The victim, Desktop Windows Manager, was introduced in Windows Vista as a novel way for apps to displays pixels on a screen. Instead of drawing directly onto a primary display, apps draw to off-screen surfaces in video memory, which are then rendered onto a desktop image.
"Through desktop composition, DWM enables visual effects on the desktop as well as various features such as glass window frames, 3-D window transition animations, Windows Flip and Windows Flip3D, and high-resolution support," Microsoft explained in a support document.
As outlined, DWM is a critical Windows 10 feature used for visual effects and support of high-resolution displays. Those hit by this flaw have reported various symptoms, from desktop icons being rearranged and resized to a black screen that can only be fixed with a restart.
Who is affected by DWM issues?
The good news is that these DWM problems only arise under specific conditions. Microsoft outlined two unlikely scenarios that can cause the DWM.exe process to stop responding.
Scenario 1:
- You plug a High-Definition Multimedia Interface (HDMI) monitor into a laptop computer that is running Windows 10.
- The monitor is configured to operate at 4K resolution.
- You repeatedly play a 4K H264 video in Movies & TV on the computer.
- In Control Panel, you open the Advanced settings screen of the Power Options item, and then you set Lid close action as Do nothing.
- While the 4K video is playing back, you repeatedly close and open the computer lid.
Scenario 2:
- You connect two 4K monitors to a Thunderbolt 3 docking station.
- You connect a laptop that has a 4K solution monitor to the docking station, and then you configure a triple 4K display configuration in either "clone" or "extend" mode.
- You repeatedly undock and redock the laptop.
What to do now
Microsoft is working on a solution but didn't say when it would arrive. We suspect it will be released in a Windows 10 update in the coming weeks or months.
Until then, look over the two scenarios above and make sure not to replicate those actions. If you have a 4K laptop, or are connected to a 4K monitor, you'll need to be extra careful.
