If you downloaded some gadgets for Windows Sidebar that utilizing Flash Player and you are in a 64-bit Windows environment, chances are your gadgets won’t work properly for you. It is because flash player has never come out with a native 64-bit Flash Player that supported the Windows Sidebar.
So if you face this problem, it can be easily get solved by a few steps:
1) Close the sidebar.exe (By Task Manager or manually closing all gadgets)
2) Starts the sidebar.exe in Program Files (x86) folder instead of the one in Program Files.
3) Try to add the gadgets that didn’t work previously and enjoy it!
The idea of the trick is that you start up the 32-bit Windows Sidebar instead of the 64-bit one, so Flash Player can run in the gadgets that utilizing it. Hope it helps!