msk0 interface stops working when downloading

Hey guys,

After banging my head against this for a few hours, I've decided to ask for help.      I installed FreeBSD 8.1 amd64 on a Shuttle J1 4100 system (tech specs here http://us.shuttle.com/J1_4100.aspx).   I installed from DVD and the install went fine.

I notice when I pkg_add -r anything,  the network stops responding. 

Some details:

1) I can reproduce it 100% by downloading a large file.     low traffic like the SSH connection does not trigger it.   I think it's being triggered by traffic above a certain rate. 
2) I can recover by restarting the network interfaces (/etc/rc.d/netif stop;  /etc/rc.d/netif start)
3) I see no errors in dmesg or /var/log/messages.  Nothing at all.
4) I've tried the following in /etc/sysctl.conf:
net.inet.tcp.tso=0
net.inet.tcp.inflight.enable=0

and in /boot/loader.conf:
hw.pci.enable_msix="0"
hw.pci.enable_msi="0"
hw.bce.tso_enable="0"

But the problem persists.

The interface is identified as:

mskc0: <Marvell Yukon 88E8057 Gigabit Ethernet> port 0xe800-0xe8ff mem 0xfebfc000-0xfebfffff irq 17 at device 0.0 on pci2
msk0: <Marvell Technology Group Ltd. Yukon Ultra 2 Id 0xba Rev 0x00> on mskc0
msk0: Ethernet address: 80:ee:73:01:60:7d
miibus0: <MII bus> on msk0
e1000phy0: <Marvell 88E1149 Gigabit PHY> PHY 0 on miibus0
e1000phy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseT, 1000baseT-FDX, auto
mskc0: [ITHREAD]



Does anyone know what could be causing this or how I can resolve it?   Any help is appreciated, thanks.


--Andy