Xavier: I use command line options to download a web site.
The options: -%P0 or %P0 or '%P0' are not working at all.
WinHTTtack does not working with an unchecked 
option 'Attempt to detect all links' too.

The full parameters list (it used in *.bat file so I use %
%):

c:\\tools\httrack\httrack.exe -F "Mozilla/4.0 (compatible; 
MSIE 6.0; Windows NT 5.0)" -N1 -I0 -C0 -o0 -%%P0 -%%F "" -%
%l "en, *" %url% -O "C:\Temp\Manual","C:\Temp\Manual" 
+*.png +*.gif +*.jpg +*.css +*.js -%%A 
php3,php,php2,asp,jsp,pl,cfm=text/html

I think that it is a bug. I use the 3.23 version.