This is an old IBM Thinkpad (Win 98se), which, until today accessed the internet via a Belkin PCMCIA ethernet card connected to a Linksys wired router. It was also set up to share files with another PC (XP Home). The router is connected to the internet via a cable modem. There are also 2 other PCs which connect wirelessly through a Linksys WAP. When I couldn't connect to the internet from the laptop, I checked the other machines and they all could connect fine. After restarting the laptop and rebooting the router, the problem continued. I checked ipconfig and found that the IP address and subnet mask were showing zeros and the space next to "default gateway" was blank. I also tried a different ethernet cable hoping for a good old fashioned defective wire but that was not it. The indicator lights on the connection to the card (labeled "link/act" and "100") are both lit. I attempted ipconfig/release and ipconfig/renew but there was no change.
Does anyone have any ideas?