Edited - SOLVED! I noticed my registry cleaner severely stalling at this new entry and it dawned on me that it must be in error - the recommendation was for a value of
"file://C:CopyAsHtml.js" (with the quotes and all). This is clearly (now, after the event!) an HTML file reference, with no place in the registry. The correct value is:

The whole show then works as advertised.

I have been trying to implement the following javascript in the (98SE) IE6 context menu, to copy the html code for the selection to the clipboard:
<pre><SCRIPT LANGUAGE="JavaScript" defer>
//Get the selected Html source of the window object
//where the context menu item was executed
var selectedHtml=(external.menuArguments.document.sele ction.createRange()).htmlText;
// Set the clipboard with selected HTML, if there is any
if(selectedHtml!= "")
external.menuArguments.clipboardData.setData("Text ",selectedHtml);

I got the code from here and the feedback there seems to indicate no problems with it. The new context menu item appears OK with a right-click, but I can't get anything onto the clipboard, nor can I see any JS errors pop up - but this might be due to my IE settings, which I'm not sure of how to fiddle. Any ideas on what might be going wrong, please?