Article ID: 259449
When you click Start, and then click Help, you may receive the following error message:
Cannot Open the File: %system root%\Help\Windows.chm.
To resolve this issue, extract a new Windows.chm file from your original installation media. For additional information about how to extract files, click the article number below to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/129605/EN-US/ )How to Extract Original Compressed Windows Files