This may be specific to Windows 7 64Bit Ultimate, and I run as Global Administrator, but, in your post, after "Click "Enabled" and click "Show" under List of Disallowed Control Panel Options.", for me it is only necessary to type in the exact title as it appears in the Control Panel, and then Apply.
Fwiw, if the op only has the home edition fo Windows 7, it can be done through the registry, Gpedit being a gui to that feature.
The "user Accounts" is difficult, as it needs some editing:
If any readers try this, the usual warning, Back up the registry first!
Open the Start button, and Run.
In the box, type regedit
Go to
_CURRENT_USER\Control Panel\don't load
Right click to create a String Value "nusrmgr.cpl" (right-clicking in the open area).
Right click to modify the value of created string nusrmgr.cpl. and set the Value Data as No in the textbox provided and click on 'OK' .
For hiding the other Control Panel features, it is simpler. :
Again, in the registry, navigate to:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Control Panel\don’t load
If not obvious, you will need to know the name of the icon. You can search for *.cpl , which are all found in Windows\winsxs\wow64 or amd64. The description usually is enough to see which .cpl file will turn off the icon. Then just enter a new string with a value of the icon name. This must be exact such as Firewall.cpl