File copy errors

We are currently experiencing some failures with copying files (files
typically over 100mb in size) up to one of our file servers, and we're
hoping that someone has seen the problem or has some advice.

The server is an HP Proliant DL360 G5 (with two Broadcom Gigabit NICs)
running Novell Netware 6.5 with SP8. The typical CPU load is below 20%,
however packets per second is typically in the 50k-75k packets per
second range during the day.

On Windows XP with Novell Client 4.91 SP5, we receive: "Cannot copy
<filename>: The specified network name is no longer available."

On Windows 7 with Novell Client 2 SP1 (IR8), we receive "Can't read from
the source file or disk."

The symptoms are more typical when the traffic is higher on the server
and in areas with faster switch hardware. There is no consistency with
when (during the copy) we see the error and there seems to be no affect
on the server itself. Even though we have not seen errors on the
monitor's NIC stats, we have tried moving from one server NIC to the
other to see if it is somehow related to a NIC. The errors are
repeatable on both the server's internal drives as well as the connected
SAN drives.

In addition, we have another server with almost the same configuration
(same hardware, SAN connection, OS version and patch level) that is not
having this problem at all. The main difference is that the load on
this 2nd server is very small compared to the server where we see the
copy errors.

Any info is greatly appreciated.