• Close Windows Sidebar. To do so, right-click on the Sidebar icon in the Notification area and click Exit
• Open an elevated Command Prompt window. To do so, click Start, click All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
• In the Command Prompt window, type the following and press ENTER:

regsvr32 msxml3.dll

Similarly, run these commands:

regsvr32 scrrun.dll

regsvr32 jscript.dll

If the registration was successful, you'll see the message DllRegisterServer in <filename> succeeded for each command executed. Open Windows Sidebar (sidebar.exe) and check if the problem is resolved.