[CentOS] tg3 ethernet card drops connection under heavy load

We have an HP DL360 server with dual on-board Tigon3 ethernet cards.
We are using eth0, eth1 is unused at the moment.  Sometimes when the
network interface is under heavy load, for example moving large file
transfers over rsync or NFS, the network interface stops working and
we lose all connection to the server.  The only solution at this point
is to jump on the console and restart the network interface.  I have
not found anything in the log files to indicate what is causing this.
Has anyone else experienced something similar?  Or perhaps you know
how I could troubleshoot this?