Visual Studio - An error occurred loading this property page

If you found out that the "Design, Split, Source" buttons are not available anymore, your first reaction would be to take a look at Tools->Options->HTML Designer, at this point probably you encounter with this error message:
"An error occurred loading this property page"

I encountered with the error and it was resolved by running "devenv /setup" in Visual Studio 2008 Command Prompt and restarting Visual Studio. The "Design, Split, Source" buttons came back to the right place after running that command.

Visual Studio - An error occurred loading this property page