Tkanks for trying to help but this file makes my problem worse.
At startup, when Sidebar tries to launch, I get several errors, "C:\Windows\system32\sfc_os.DLL is either not designed to run on Windows or it contains an error." My system starts fine but without Sidebar. When I try to launch Outlook, I get the error again, but Outlook seems to run fine. Later, when I "run sidebar", the program launches and runs just fine.
I have reset the permissions but apparently I need a different version of sfc_os.dll.