Spurious help file opening

[xoggoth]

Opening context sensitive main help file as follows:

Help.ShowHelp(Me, HelpProvider1.HelpNamespace, HelpNavigator.KeywordIndex, pr.PicTopics(CurrentView) )

Also using standard HTML Help format for some content elsewhere:

Help.ShowHelp(Me, InstTextFile)

Problem is, if this 2nd help is already open when users click main help, the main help opens twice, once properly and once using the window definition of the 2nd help, i.e. with no contents page. Unfortunately it is this 2nd one that appears on top.

How can I check if first help is still running so can close it and without confusing with any help from another app?

Thanks for any ideas.