as a follow up, looks my problem is solved... I was using a DFE-530TX+ adapter which uses the 8139 driver. I switched, and am now using the internal intel ethernet adapter that comes on my motherboard, and all looks well. What tipped me off was that I retried the operations I was doing, but instead of using nfs, I sftp'd from my source machine over to my machine. The machine froze in the middle of a hugh file. In searching for 8139, I found where the machine locking up is a known problem.
-- System hangs when copying to NFS mounts https://launchpad.net/bugs/71212 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
