Hi there,
I realise that this thread is quite old, but it has been most helpful for me. I had the same problem with the sidebar and mixing a bit of everything that you guys have said I managed to solve the problem.
I don't know if anyone is still looking for a solution, so I'm going to put here what I did and in which order, I'm saying this because I had tried some of the things separately and it didn't work. So...
- First of all, if you have the Sidebar running, close it and exit the program.
1. type cmd in the Start menu's white (Start Search) line and right click cmd (at top) and click Run as administrator.
2. In the command prompt, type regsvr32 msxml3.dll and press Enter
3. Click OK
4. In the command prompt, type regsvr32 scrrun.dll and press Enter.
5. Click OK
6. In the command prompt, type regsvr32 jscript.dll and press Enter.
7. Click OK
8. In the command prompt, type regsvr32 msxml4.dll and press Enter
9. Click OK
10. In the command prompt, type regsvr32 msxml6.dll and press Enter
11. Click OK
12. Reset Internet Explorer to its original settings.
13. If you are using aero, deactivate it.
14. Reboot your computer
15. Reactivate aero.
Your sidebar should be working fine now.
Thanks to all the people that gave input to sove this problem!