Cloud Box Network Card "dying" under load, fixed with ifconfig down && up

I've been having an issue with one of my cloud hosted boxes. Under load - almost randomly - the machine will refuse to take connections. I then log into the machine and run "ifconfig eth1 down && ifconfig eth1 up" and the problem is solved.

I can't seem to glean any information from the logs. Nothing related is outputted to dmesg or syslog.

This is an 2 - Core Ubuntu 12.04 box with 2GB of ram running postgres, and under load it will typically have ~145 concurrent connections.

Here is a log - http://pastie.org/7933304

From top to bottom each log has

uptime free iostat -x vda2 -t echo "Connections:" netstat | grep app3 | wc -l echo "------" sleep 5

I'd love if there was come configuration I could change without scrapping the box.