When you open Folder Options and select the View tab, you can check or uncheck the Display the contents of system folders box.

To check this option via the registry:

Copy /Paste the following to a WebViewBarricade.reg file:

REGEDIT4

\[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\]
"WebViewBarricade"=dword:00000001

2. Merge the WebViewBarricade.reg file with the user's registry or run regedit /s WebViewBarricade.reg.

3. The user must log off and log on for this setting to take effect.

To uncheck this option via the registry:

Copy /Paste the following to a WebViewBarricade.reg file:

REGEDIT4

\[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\]
"WebViewBarricade"=dword:00000000

2. Merge the WebViewBarricade.reg file with the user's registry or run regedit /s WebViewBarricade.reg.

3. The user must log off and log on for this setting to take effect.

NOTE: See How do I set the 'hide' options of the View menu via the registry?