Hi everybody!
I met the same problem trying to download a web site with css and images...and
I found the solution:
keep the newest version of httrack (3.4.1) and simply add options to download
those kind of files (just like lounching the console). 
here is an example:
httrack some_url -O some_outup_dir +*.png +*.gif +*.jpg +*.js
-ad.doubleclick.net/* -mime:application/foobar

hope I helped you!