> For this project we have to download and archive 
sites 
> of Dutch political parties. To perform the download 
we 
> use Httrack version 3.05 (Unix-version). 
> With this Unix version we have encountered a problem 
> we can’t explain ourselves:
> Httrack seems to interpret internal links sometimes 
as 
> external links without any obvious reason.

Always look at the hts-txt.log file:

16:07:32        Info:   Note: due to www.cda.nl remote 
robots.txt rules, links begining with these path will 
be forbidden: /articles/ (see in the options to 
disable this)

Therefore, use -s0 to disable robots.txt behaviour