I've had this happen before, but it's happening again and 
it's rather annoying.

Some times I've tried to download some stuff that was just 
very very slow.  Rather than wait for it, I'll just click 
the stop button a couple times, to stop immediately.

I figure I'll just do it some other time when the site is 
faster.

But sometimes when I come back, httrack just exits when I 
select the site from the drop down list.

No error messages.  Nothing.

Something data file is being corrupted upon exit, I guess. 
And later httrack is just too stupid to deal with it 
properly.

The only way to deal with it (that I know of) is to delete 
the directory and the stuff it's already downloaded and 
start over.