At "System property",select "Hard Ware",then open "Device Manager" and update Ethernet adapter card Driver.

Note: 1ˇ˘You don't need to install driver for the onboard lan chip RTL8103E
   WindowsXP system file path: MB\LAN\ 8103E\xp 
   Windows2000 system file path: MB\LAN\ 8103E\2k 
 
     2ˇ˘You don't need to install driver for the onboard lan chip 
       RTL8100C in WINDOWS 2k/XP.(The driver is built in the 
       system)  