This is a great piece of software - it's helped me to create offline backups of
important websites and to cache those that get a lot of traffic (speeding up
access a lot!). However, it has done this:

HTTrack 3.49.1 closed at '.\htscache.c', line 401
Reason: zip_zipCloseFileInZip_failed

Stack trace:
unknown [WinHTTrack]
unknown [WinHTTrack]
coucal_dec [libhttrack]
coucal_dec [libhttrack]
coucal_dec [libhttrack]
coucal_dec [libhttrack]
hts_is_available [libhttrack]
hts_is_available [libhttrack]
copy_htsopt [libhttrack]
copy_htsopt [libhttrack]
hts_main2 [libhttrack]
unknown [WinHTTrack]
htsthread_init [libhttrack]
endthreadex [MSVCR90]
endthreadex [MSVCR90]
BaseThreadInitThunk [KERNEL32]

64-bit Windows 10, version 3.49-1.

Also, the CAPTCHA that I've been shown on this page could be pre-processed to
make it OCRable quite easily - increasing the contrast them removing hued
pixels would do it.