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

<b>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? </b>
If you press Yes, or No, the User Accounts dialog opens.

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