If you press on the Warnings tab, does it give you any more detailed information?

By the way, I don't recommend that you turn off the firewall and virus scanning features of XP if you are connected to the internet. Leave them on and poke the hole for emplode as described in the FAQ here. It's possible that the reason you're getting ethernet errors is because you've been infected by a worm that's clogging your bandwidth. (This is just one of many possibilities, I'm not saying that's likely, I'm just saying that sort of thing can happen when you turn off the firewall and virus scan.)