> When it reached the point where I wanted to stop it
> I clicked cancel and it asked if I wanted to stop
> Winhttrack and I clicked "yes" and the 150 MiB I had
> saved started going backwards as if it was
> deleting.
Only reason I can think of is files not yet downloaded.

> Before I started the download I had chosen "do not
> purge old files" under "Build" in the options. 
> Where is the "do not delete" you were talking about
> in another thread.
That's the option.

> Last time I clicked "Select (Cancel) to stop now!"
> which is flashig now too, but everything was
> deleted.  This is my second try.  
Pressing a second time is an abrupt stop. You can not continue/update.

After Canceling, any files not already processed will be redownloaded on
update/continue. And will be deleted off disk unless do not purge

If you want to continue a mirror later, Pause and Resume.