1. Click 'Start' and select 'Run' in the right-hand corner of the Start menu. Type 'Notepad.exe' into the text box, and click 'OK.'
2. Type 'x=MsgBox('Error Message', 0 16, 'Box Title Name')' into Notepad without the external quotation marks and include your custom error message in the 'Error Message' section (in quotation marks) and a title for the error message in 'Box Title Name' (in quotation marks). An example of an error message may be x=MsgBox('You clicked the wrong key!', 0 16, 'Wrong Key!'), as exactly written.

3. Click 'File' and select 'Save As' in Notepad. Save your error message as 'Error.vbs' to your computer, preferably on the desktop.
4. Click 'Start' and select 'Run' as in Step 1. Select 'Browse.' When the Explorer window appears, select 'All Files' from the drop-down box in the right-hand corner. Locate the error message saved in the previous step; for example, if your file was saved on the desktop, you could navigate to 'Desktop' and select 'Error.vbs.'
5. Click 'OK' in the 'Run' window. Your error message should now appear. If the error message does not appear as expected, ensure you have followed the method correctly or try creating a new error message.
6. Right-click on your saved error file, and select 'Copy'. Select 'Start,' click 'All Programs,' right-click on 'Startup' and click 'Open.' Right-click in the 'Startup' window and click 'Paste.' Your custom error message will now appear when Windows starts.