> Why? What to do? Below information from status window
> File: /download/?url=%2Fdata%2Fproduct%
> >2FBR_DC1600E_0410.pdf
> >ContentType: application/pdf

This is a known bug in httrack: links tagged "html" are 
always saved as html, because the naming process is done 
BEFORE downloading the file.. this bug will require some 
code rework, unfortunately, and hence it won't be fixed 
very quickly