>Ed,
>
>Thanks for looking at this. Here's what's reported by Help\About HTML Help:
>
>hhctrl.ocx 4.72.7323.0
>itss.dll 4.72.7309.0
>itircl.dll 4.72.7276.0
>hha.dll 4.73.8198.0
>
>Compiled with HHA version 4.72.8086
>

I definitely have a more recent HHCTRL.OCX, ITSS.DLL and ITIRCL.DLL on all the systems, whether they behave or not. It's either a fix in the HHCTRL.OCX or a registry setting, and the more I look, the more likely a registry setting appears to be the issue; I definitely have my browser on my laptop set up differently than the browsers on my desktop machines because of things like screen resolutions, what rodent is being used, and Active Desktop related configs.

>I'm also using IE 5.00.2014.0216. I think I'll try & upgrade to IE 5.5 & see how that works, but I'm rather curious as to what's changed to bring about this behaviour.
>

It's not IE 5.5