When you install Windows NT 4.0, or Windows 2000, you are given the option to change the default system date format. Once installed, there is no way to change the default system date format. The format is somehow recorded in the kernel.
Editing HKEY_USERS/.Default/Control Panel/International/sShortDate does not change the default system date. It does change the default date for new user accounts.
In the North American version of Windows NT 4.0, the default system date uses the m/d/yy format, unless you change it during install. In Windows 2000, the default format is m/d/yyyy.
The default system date is only used when no user is logged onto the local console.
Some programs may not function with the Windows 2000 default system date format, unless a user is logged on the local console.
The choice of formats are: