Restrict Access to the Passwords Control Panel
This options disables access to the Passwords icon on the the control panel, therefore stopping users from changing security related settings.

just open Registry editor by tying "regedit" in RUN dialog box and go to the following key---
Key: [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System]
and create a REG_DWORD with Value Name: 'NoSecCPL'
and change it value as described below.

Data: (0 = disabled, 1 = enabled)

At last reboot ur comp. 4 taking effect.