Take a look at FAQ#7891 'Why has my VFP Help File stopped working?'
In wich version it doesn't work? vfp 6, vfp 7 or both?

>Help! My VFP 6/7 help no longer works. It was working fine yesterday and today it does not respond at all. I reset the computer, set help to xxxxxx.chm, set help on still no response. I can double click the chm file in explorer and it will load but not from F1 or the help command. I installed ZoneAlert yeaterday, I terminate ZA and still no response. Any suggestions???
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>Glenn