What exactly is the problem? Does network connectivity drop? Does the machine lockup?
In device manager how many network cards are listed? Look for any items with question marks.
Are you running on a 10/100 MBS auto-sensing network? Have you tried to disable auto-sensing and configure to a fixed speed? If these possibilities don't lead you toward a solution please write back and give a more detailed description of the problem.
This was first published in March 2003