Hi,
A few hours ago, I tried to open Help and Support on Windows Vista, but I received this error:
After a few minutes research, I found a fix for this error and thought I would share it with the rest of the ExtremeTech.support - Free PC Help community, as this is seemingly a very common problem.
To fix this error, you will first need to download and install a file extraction program such as WinRAR. Then you will need to download and extract (Right click | Extract here) the registry fix from here: http://www.chris123nt.com/guides/RTM_Fixes/Fix_Help_and_Support.zip which will leave you with a registry file and an instructions file. The registry file merges into the Windows Registry and "...re-associates the .xml file type with its default settings.", according to Kristian Kenney's blog.
Next double click the registry file, and Vista will prompt you to allow or disallow the merging of this registry file into the Windows registry; allow it (don't worry - it's safe!). Now open up Help and Support, which should now be fully functional :).
Hope this is helpful,
Liam.