I tried pause download, tried cancel. Still doesn't work. 
WinHTTrack (3.33 and 3.42) not only restarts non-html files, it also restarts
html files. 

I've enabled "Do not purge old files" and 
"Store ALL files in cache". 

My understanding of WinHTTrack is everytime it needs to update/resume a
download, it looks at the cache (new.zip) and decide which directory (of the
remote site) to continue donwload. 

However when i tried to resume a download, the filesize of new.zip didn't
continue to grow, instead it was renamed to old.zip and a new new.zip is
created (Is this what its suppose to happen?) And therefore download re-starts
from the beginning.