just thought I'd post this for anyone who has similar problems to me. When any distro detects my nic card, it always autonegotiates to 100Mb full duplex. For some strange reason, my router will only talk to this or any pc at this location (in the den about 30+ feet from the router) at 10Mb. All other pc's on the router talk at 100Mb. Go figure!. So I edited /etc/rc.d/net/eth0 (or eth1 etc if that is connected to the network) and added the following lines:
mii-tool eth0 -F 10baset-fd
On boot up, the nic negotiates via DHCP and communicates no probs. I did try ethtool, but that doesn't seem to work with any of the nic cards I have tried.
Hope this helps anyone else with this prob. There are probably other ways to do this but I found this the easiest.