According to http://devel.squid-cache.org/ntlm/squid_helper_protocol.html a message parameter in the BH (broken helper) reply is mandatory. Squid dies if a message with only "BH\n" is sent to it.
Created attachment 2223 [details]
Add missing messages.
These are cut-n-pasted from the debug messages right above.
(In reply to comment #1)
> Created an attachment (id=2223) 
> Add missing messages.
Pawel, I'm adding your patch to the FreeBSD net/samba3 port. Hope, it'll solve the issues with ntlm_auth you have.
With best regards,
Committed to 3-2-test in 098380760d20bad2a45c3b12ab2a5e4d2b856175,
to 3-0-test in ef51a97332506c028b8689f7516234855d3d1b83 and added a patch for the same issue in 4-0-test in b6bb7621053bccc9d06b1b2ee9f71b1b1acf3b70