I just got my X5000 and keep having to delete my network connection from devs/netinterfaces after a reboot and then reboot again and add a new one every time I power off or reboot.
Why? Well because it doesnt seem to respond after I get it added and then do a reboot. Every single time. Symptoms are I add the RTL8169 device using the "New Connection" tool in System/Internet, it works, I reboot and it doesnt work. Repeat and repeat.
Its a PCIe card that came with my X5000 from Amiga on the Lake. I tried reseating it, but it just does the same, works for one cycle before I have to delete the setting and add it all over again.