> I am unable to archive the whole site in one
> sitting, and therefore need to make use of the
> "continue interrupted download" option. My folder
> however gets smalller after some updates. Why????> 
> Could someone please explain to me how I would
> continue without going backwards???

It's possible some sections of the website are changed or removed?  You could
try the option "Build > Do not purge old files" which should prevent deletion
of files, although they may no longer be properly linked to after an update
(but you'll still have the files at least).