Another "siocsifflags" problem

I cannot get eth0 up on Linux kernel 2.6 at all. I was able to do so on 2.4 with no problem, but both on an upgrade to 2.6, and a fresh install of Mandrake 10.1 (which includes 2.6) anytime I enter the command "ifconfig eth0 up" as root, I get this:

SIOCSIFFLAGS: Function not implemented

I've tried every setting I can think of, DHCP, static IP, and so on. I went through the Mandrake wizard many times. I removed the connection completely and added it back in many times. I think I tried everything besides recompiling the kernel.

Can someone tell me what I'm missing?

What kind of NIC are you using?

I used two different types. One that was intergrated with my motherboard, and a seperate ethernet card. Note that there was a complete reformat and installation of my distro between me trying both cards. I'm not sure of the exact make or model on the seperate one, but it was fairly standard. My motherboard is a Soyo P4X400 Dragon Lite.

I figured it out. ACPI messed everything up.