Unable to open.chm files

Found this link that is just the key to .chm files not opening under XP

http://www.drexplain.com/press/articles/error_accessing_and_displaying_chm_files_reasons_and_solutions/

The site has a listing of the probable causes for your .chm files not opening

A security update for Windows XP® may block access to CHM files

Windows XP® security update blocks active content in CHM files to protect your system security. Additional information is available here.

Solution: Run Windows Explorer, right-click on the CHM file, and select Properties from the popup menu. Click on the Unblock button immediately below the Advanced button on the General page. Click Apply to show the content. Once the CHM file has been unblocked, the Unblock button disappears.