Hi,
Try this : click on start and in the search box type gpedit.msc which will take you to the group policy editor.
Now go to User Configuration > Administrative templates > Control Panel
In the windows on the right, double-click "Show only specified Control Panel Items"
In the new Window mark disabled then click on Apply and OK
Now see if the control panel works, or restart computer and see if works.
Let me know,
David