Windows 7 sidebar with gadget stops working if User Account Control (UAC) is disabled as shown below. Microsoft may have done this to prevent users from installing any malicious unsigned desktop gadget in windows.
But here I have given a solution to make Windows7 sidebar with gadget to work when UAC is disabled or turned off.
Step 1: Click on Start Menu go to Run type regedit and Hit Enter.
Step 2: In the Registry Editor follow the below navigation path
Step 3: Right Click on right side of Registry editor. Click on Create A New DWORD(32 Bit Value) with name “AllowElevatedProcess” and set value to “1”.
Step 4: Exit registry editor. Then Right click on desktop and Click on add desktop gadgets. as shown in figure below
Now Your Desktop Gadgets and sidebar will be Enabled.