Computer Recognizes NIC But Can’t Ping

I have a computer running Windows XP with a 3com 10/100 NIC installed. I recently installed a USB 2.0 card and the computer still recognizes the NIC, but I can’t get on to the network now and when I try to ping 127.0.0.1 it times out with no reply. I can start up in safe mode with networking and successfully ping the card then, but when I boot up in normal mode it still doesn’t work. Removing the USB card had no effect. Any suggestions, anyone?