Faced this problem recently that all of a sudden when I started my computer the desktop gadgets started displaying incorrectly. I am using Windows 7 Professional but got this problem after one and a half years of using it.
The UAC is set to default level and sfc scan shows no errors.
I have tried restoring the gadgets from the start menu, which didn't solve the problem. Also I have tried turning windows gadgets on and off from Windows Features but that didn't work either.
I tried re-registering the dll's but that also didn't work.
Got this problem after I un-installed McAfee Security Center as it had expired. I have used Mcafee's MCPR tool to remove any additional files which are leftover by mcafee, but still my gadgets aren't working properly.
Let me know if there is a solution for this problem.