You can control the behavior of Dr. Watson by editing the registry at:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\AeDebug\Auto

A data value of 0 in this type REG_SZ causes the system to display a message box notifying the user when an application error occurs. A data value of 1 (the default) causes the debugger to start automatically.

You can disable the good doctor by deleting the AeDebug subkey. If you wish to re-enable it, type drwtsn32 -i from a command prompt. v