It's hard for me to pinpoint exactly what page had this 
problem in particular because it only has happened to 
me on crawls of large websites with hundreds or 
thousands of pages.  I think only one or two of those 
pages is actually at fault, but the problem cascades 
upon itself.

I think I can set up an example of such a 'faulty' 
link, though, on my own website if that helps.

Lastly, as an FYI I've found that httrack can't 
successfully handle the javascript used by archive.org 
for any of its archived sites to get images or links 
behind the starting page.  That may be a good 
thing...I hope that place stays around for a long time 
to come.