> I'm already controlling this from VB using the command 
line 
> shell. The command options I am using are :
> 
>  -%c10 -x -o0 -Z -I0 -%I0 -p1 -l -N0 
> 
> This still prompts for whether I want to update the cache 
> in a DOS window, where the cache file exists.
> 
> Any further thoughts?> 
> Stevod

This may or may not work, but have you tried piping the 
appropriate keyboard reply character to the command line 
you create above?  I'm thinking about the i/o redirectors 
built into the command shell like |, <, <<, >, >>.  I think 
you could try something like:
-create a text file containing a single 'letter' response 
(Say, response.txt with just one 'a' in it.)
-then try C:\> type response.txt | httrack -%c10 -x -o0 -Z -
I0 -%I0 -p1 -l -N0 

or maybe:
C:\> httrack -%c10 -x -o0 -Z -I0 -%I0 -p1 -l -N0 < a

Search google for more...
<http://www.google.com/search?hl=en&lr=&ie=ISO-8859>-
1&q=dos+piping+input
<http://www.glue.umd.edu/~nsw/enpm808c/dos.htm#Pipe>