I get the same error. This is exactly what happens:

* chose get separated file
* entered url (of one file) in the box(not using add url)
* clicked on "next" and then "finish" (already connected via
modem)
* HTTrack started downloading the file (large file 65 MB)
* after a while click "cancel"-"cancel" to interrupt download
* message comes up "want to revert to previous catch or not?"
* before clicking on anything program crashes and the error
message others reported comes up.

Hope this helps Xavier and you can reproduce it. I tried it
a few times and the same thing happens every time. op is xp
prof.

Otherwise a great program, I use it a lot, even for single
large file download!