Problem with IBM EMAC driver on Ocotea board

I am trying to use the Gigabit ethernet interface on the IBM EMAC driver with no luck. Below is my configuration:

Board: ppc 440GX Rev. B PPC440GX EVB (Ocotea) GNU/Linux Kernel: Vanilla 2.6.10

I can get the GigE ports to work with U-Boot, but once the linux kernel loads, and the Linux driver is running, the GigE ports no longer work. It looks like they can receive data, but not transmit. Also, the 100Mb ports work fine under the linux driver.

Does anyone have experience with Gigabit ethernet on this board? Is there a patch or trick I need to make it work?

Thanks in advance!