Comment 4 for bug 236268

You need to get the newest igb drivers from here: http://sourceforge.net/project/showfiles.php?group_id=42302&package_id=237808
You need, at least, version 1.2.44.3.

Version 1.2.24 (which is linked as the newest version on the Intel homepage *sigh* http://downloadcenter.intel.com/detail_desc.aspx?agr=Y&DwnldID=13663)
still has a bug, because of which the nic's will only work after "ethtool -K <if> tx off".
See: http://<email address hidden>/msg00101.html

Now, this version "only" has to make it into the Ubuntu packages ...