I've experienced this problem with both the Linux and the 
Windows versions of httrack. While copying big sites 
httrack goes into an infinite loop while scanning the same 
page over and over again and not downloading any new files.

The two sites in question is:
- <http://www.php.net/manual/en/> (Linux)
- <http://drupal.org> (Windows XP)

While copying the PHP Documentation site, httrack 
misinterprets the 'en' in the URL and starts adding other 
language characters to the URL. This causes the loop as 
httrack tries to download several files that do not exist.

While copying the Drupal site, httrack gets stuck on one 
node in the website and never gets off that node (can't 
recall now).

I left httrack for over 24 hours on each of these sites 
with no effect, later on I used wget to mirror the sites 
and it worked perfectly (just very slow).