It is one of the special startup options for troubleshooting.
"Diagnostic startup" is one of the special startup options of Windows for troubleshooting (problem-solving).
In Safe Mode, Windows incorporates drivers of the standard VGA, keyboard and mouse at its startup. When "Diagnostic startup" is selected, Windows incorporates, in addition to the above drivers, almost all device drivers from what it supports except network related drivers.
If the system hangs up frequently or repeats abnormal termination, you may have a chance to solve the problem by narrowing down the problematic part of the software with
the use of such startup options as "Diagnostic startup" and "Selective startup".
For information, when you select "Diagnostic startup", the changes you made on the contents of the system environment files with "System Configuration Utility" will be cleared (restored to the initial values).
Before selecting "Diagnostic startup", you need to note the current settings or to back them up so that you can restore the system to the current settings at any time.
On Windows 98 and Windows 98SE, you can create the backup of the current settings by clicking the "Create Backup" button on the "General" tab.
On Windows Me, you can back up the settings by creating "Restore Point" by clicking the "Launch System Restore" button on the "General" tab on "System Configuration
Since "Diagnostic startup" is the startup mode for troubleshooting, it is not suitable for the operation of application programs excluding part of applications such as system diagnostic programs.
To start Windows with "Diagnostic startup", follow the procedures as below.
1. Click the "Start" button and then click "Run".The dialog box of "Run" appears.
2. Type "msconfig" in the text box of "Name" and click the "OK" button.
3. When the dialog box of "System Configuration Utility" appears, click the option button of "Diagnostic startup" and then click the "OK" button.
4. When the dialog box of "Do you want to restart your computer now?" appears, click the "Yes" button.
Windows restarts automatically in the "Diagnostic startup" mode.