network time outs

Hi,

We have a DS20E running T64 5.1 PK6.  A year or two ago we installed a
gigabit nic (I don't know the model off-hand but can get it if need be).
Lately we've noticed that we get time outs when transferring large files
(several gb) from this machine to some other machine (e.g., ftp, rcp,
legato, etc.).  Using collect/collgui I don't see any particular issue
with the nic/network (collissions, bandwidth %, etc.) and with ifconfig
I can't tell much about the nic's config.  The boot message has this:

Avmunix: alt0 at pci0 slot 8
vmunix: alt0: DEGPA (1000BaseT) Gigabit Ethernet Interface, hardware
address: 00-60-CF-21-71-90
vmunix: alt0: Driver Rev = V2.0.16 NUMA, Chip Rev = 6, Firmware Rev =
12.4.12
vmunix: alt0: 1000 Mbps full duplex Link Up via autonegotiation


Transfers of smaller files even a few hundred mb seem to go just fine.

What sorts of things can I start poking at to see if I can find a
problem.  Other machines on the network don't have this problem -- only
this one so we suspect some configuration setting.  How can I find out
information about the nic (speed, duplexing, etc.) while the OS is
running (i.e., not from the boot-prompt)?  If I remember correctly this
card can only be set to autonegotiate (usually we force the nics on our
unix boxes to a certain speed and duplexity).

Thank you all very much!

Andy