here is the log from the failing site:

HTTrack3.44-1+htsswf+htsjava launched on Sat, 14 Jan 2012 02:02:43 at
<http://yukongis.ca/> +*.css +*.js -ad.doubleclick.net/*
-mime:application/foobar +*.gif +*.jpg +*.png +*.tif +*.bmp +*.zip +*.tar
+*.tgz +*.gz +*.rar +*.z +*.exe +*.mov +*.mpg +*.mpeg +*.avi +*.asf +*.mp3
+*.mp2 +*.rm +*.wav +*.vob +*.qt +*.vid +*.ac3 +*.wma +*.wmv

(winhttrack -qiC2%Pns0u1%s%uN0%I0p3DaK0H0%kf2A25000%f#f -F "Mozilla/5.0
(Windows; U; Windows NT 5.0; en-US; rv:1.1) Gecko/20020826" -%F "<!-- Mirrored
from %s%s by HTTrack Website Copier/3.x [XR&CO'2010], %s -->" -%l "en, en, *"
<http://yukongis.ca/> -O1 C:\www\yukongis.ca +*.css +*.js -ad.doubleclick.net/*
-mime:application/foobar +*.gif +*.jpg +*.png +*.tif +*.bmp +*.zip +*.tar
+*.tgz +*.gz +*.rar +*.z +*.exe +*.mov +*.mpg +*.mpeg +*.avi +*.asf +*.mp3
+*.mp2 +*.rm +*.wav +*.vob +*.qt +*.vid +*.ac3 +*.wma +*.wmv )

Information, Warnings and Errors reported for this mirror:
note: the hts-log.txt file, and hts-cache folder, may contain sensitive
information,
 such as username/password authentication for websites mirrored in this
project
 do not share these files/folders if you want these information to remain
private

02:02:43 Warning:  Previous file not found (erased by user ?), recatching:
yukongis.ca/
02:02:44 Warning:  Previous file not found (erased by user ?), recatching:
yukongis.ca/
02:02:44 Warning:  Previous file not found (erased by user ?), recatching:
yukongis.ca/
02:02:45 Error:  "Internal Server Error" (500) after 2 retries at link
yukongis.ca/ (from primary/primary)
02:02:45 Info:  No data seems to have been transfered during this session! :
restoring previous one!