TDR is the Timeout, Detection, and Recovery component in Windows. What happens is the Graphics Display driver for the installed graphics card stops responding. When this happens, windows will stop and restart the driver to fix the problem.
The most common reason for this issue is that the graphics device is being overloaded or used beyond its capabilities.
This happens most often when playing graphic intensive games, but can happen with any process that uses a large amount of graphic resources, such as when editing or creating videos.