The Microsoft DirectX graphics kernel subsystem (Dxgkrnl.sys) records display driver-related errors, assertions, warnings, and events to a log in memory (in Watchdog.sys).
In addition to recording information to a log, by default, the checked-build version of the DirectX graphics kernel subsystem breaks into the attached debugger if errors or assertions occur. By default, the free-build version of the DirectX graphics kernel subsystem only records errors and assertions to the log and does not break into the debugger if errors or assertions occur. You can change this default behavior by first creating the following REG_DWORD entries in the registry:
To make the debugger start if errors or assertions occur, you should set the value of BreakOnError or BreakOnAssertion to 1 (TRUE) respectively. To make the debugger not start if errors or assertions occur, you should set the value of BreakOnError or BreakOnAssertion to 0 (FALSE) respectively.