After updating to 13.04 all my awesome pam_mount CIFS volumes to my Novell SUSE servers stopped working. Here is how I fixed it. It should also work for you if you are having issues. There is an undocumented (at least in the man page) option for CIFS mounts called sec. You can set it to ntlm or lanman. Try using either one and see if it can help fix your issue.
mount -t cifs -o sec=ntlm,uid=userhere,gid=100,dir_mode=0700,username=userhere,password=passwordhere //server/share/path /media/userhere/path
I you use pam_mount (I highly recommend it, especially in a business/educational environment) here is my default pam_mount.conf.xml file that I use. This file should go in /etc/skel so that all users use the file. You will also have to update this for all of your existing users.
<?xml version="1.0" encoding="utf-8" ?>
<volume user="*" options="sec=ntlm,uid=%(USER),gid=100,dir_mode=0700" fstype="cifs" server="server" path="share/%(USER)" mountpoint="/media/%(USER)/share" />