I have exactly the same problem

I'm trying to mirror a site across a VPN.
If I enter username:password@192.168.0.152/ in IE I can 
access the site, and if I enter the same URL in IE 
favourites and select offline replication again it works 
fine.

However when I enter username:password@192.168.0.152/ as 
the URL in httrack it gives the following in the log:


15:41:33 Error:  "Access Denied" (401) at link 
192.168.0.152/ (from primary/primary)
15:41:33 Info:  No data seems to have been transfered 
during this session! : restoring previous one!

Is this really because httrack needs to support another 
form of authentication? Is IE really doing something 
special that httrack can't?
Many thanks
Jonathan