It sounds like you have a corrupt winsock entry. If you get the SVCHOST.exe error at start up try this.
Type regedit then click OK
Delete the two registry keys listed below...
** Restart the computer
Click Start/Control Panel/Network Connections
Right click on your Local Area Connection icon and left click on properties
Click on the Install button
Select protocol and click Add
Click the Have Disk button
Type "c:\windows\inf" and click OK
Select Internet Protocol TCP/IP and click OK
close the properties window and restart the computer
Your Network card should now properly request the IP address from your routers DHCP server.