See if http://support.microsoft.com/?kbid=896358 helps.

>Hi Tommy,
>
>Funny you should mention this, but I've been having problems with HTML Help, only fairly recently. I suspect this may be related to a Windows Update, since there have been no other changes or signs of other problems, such as file or registry damage.
>
>The particular problem I'm seeing is that I get an error when I close a HTML Help window launched via VFP's context-sensitive help mechanism in my application. No such problem with VFP's own context-sensitive help under the VFP Dev. Sys., however. I'm running a VFP6SP5 application on XP Pro SP1 + Windows Updates as of 3/27/05.
>
>I noticed this blog entry just today, further reinforcing my sense that these problems are related to Windows Update:
>
>Epic Trends - The latest security update from Microsoft interferes with HTML Help - June 20, 2005
>http://www.epictrends.com/usability-technical-writing-copywriting-multimedia/index.shtml
>
>Here are some more details from Microsoft's friendly error dialog, with the usual offer to send this report into the void:
>
>Error Signature
>AppName: foxhhelp.exe AppVer: 6.0.8161.0 ModName: ntdll.dll
>ModVer: 5.1.2600.1217 Offset: 00033aed
>
>I'd be very interested to know if anyone is running into the particular set of symptoms I've described, or to hear any suggestions about how to fix these problems. I haven't yet studied the preceding reference, nor have I decided what further steps to take. To reiterate your message, Help!!!
>
>Mike