I just resolved this problem on my setup. The description of you problem sounds very much like mine. In order to make sure you are having the same problem run ifconfig
are there a large number of errors and carriers?
If so, then it the same problem as me. There are solutions to this problem:
1. Replace the NIC. There is a problem with a few NICs which result in a large number of mis-transmitted packets. In particular the Davicom 9102 series NICs have had issues with the tulip drivers. Here is a description of the issue:
2. If you do have the Davicom 9102 series card, go to:
and download the Linux drivers for your card. If you do not have a Davicom, figure out what NIC you have and download the drivers directly from the manufacturer.
Hope this helps.