When you open Control Panel and press User Accounts many times, because it didn't open fast enough, you receive:

Internet Explorer Script Error                              An error has occurred in the script in this page.                               Line: 4                              Char: 1                               Error: Access is denied                               Code: 0                              URL: res://C:\Windows\system32\nusrmgr.cpl/nusrmgr.hta                              Do you wish to continue running scripts on this page? 
If you press Yes, or No, the User Accounts dialog opens.

To avoid this behavior, don't press User Accounts many times.