Update: problem has been resolved by Windows updates some time in spring of 2015.

This page is about a computer graphics problem on Windows, specifically an image tearing problem with DirectX 9. The problem is described at and This page has two .zip file attached to it that contain the executable or source for a program that demonstrates the problem:

To run the program:

    1. Download the .zip file with the executable and unzip it [or download the source and build it]
    2. If you wish to check it, the MD5 checksum of RedFlicker_2.0.exe is 464811777b9746962e819423d124559f
    3. Run RedFlicker_2.0.exe. [Legal note: You assume all risk running the program. I believe it is harmless and have run it without incident on two Windows 8.1 systems.]
    4. Press any non-alphanumeric key to quit, such as the escape key or space bar.

For systems without the bug, you should see a blue checkerboard. For systems with the bug, you will see some kind of red band, red streaks, or red flashing. Some program parameters can be adjusted by pressing keys while the program is running:

    • 0 - set frame rate to D3DPRESENT_INTERVAL_IMMEDIATE
    • 1 - set frame rate to D3DPRESENT_INTERVAL_DEFAULT
    • 2 - set frame rate to D3DPRESENT_INTERVAL_TWO
    • a-z - set delay between writing the buffer and unlocking it to (key-'a')*(1 miillisecond). For example, 'a' sets delay to 0, 'b' sets delay to 1 msec, 'c' sets delay to 2 msec, etc.

The delay control is a 2.0 feature.

If the source code has a mistake, I would be grateful for someone to point it out. If your system also has the bug, I'd be interested in knowing what version of Windows your are running and what your hardware graphics is. My email address is: