Squid and NTLM authentication problem

I have squid configured to work on NTLM authentication with my windows
2003 domain, it was working correctly for some time when suddenly it
stopped working. I tried the same config on another AD domain and it is
working here is the error showing in the cache.log

ntlm-auth[693](ntlm_auth.c:239): obtain_challenge: selecting DOM\DC1
(attempt #1)
ntlm-auth[693](ntlm_auth.c:243): Reviving DC
ntlm-auth[693](ntlm_auth.c:251): attempting challenge retrieval
ntlm-auth[693](libntlmssp.c:119): Connecting to server DC1 domain DOM
ntlm-auth[693](libntlmssp.c:126): Couldn't connect to SMB Server.
Error:The attempt to call the remote server failed. See protocol error
info.
RFCNBE_ConnectFailed: Connection failed. See errno.
errno:Connection refused
ntlm-auth[693](ntlm_auth.c:253): make_challenge retuned (nil)
ntlm-auth[693](ntlm_auth.c:259): Marking DC as DEAD
ntlm-auth[693](ntlm_auth.c:262): moving on to next controller


any thoughts please