problem after upgrading FC3
 

I installed FC3 kernel version 2.6.9 and it all went OK and everything was working fine. Later I upgraded my kernel to 2.6.12. When I boot my PC using this new kernel it's not connecting to the internet. I havea router which runs a DHCP server and FC3 is configured to obtain a IP address dynamically. FC3 with upgraded kernel properly gets a dynamic IP and I'm able to ping the router and all the external hosts (like www.google.com). But apart from ping nothing is working. I'm not even able to traceroute my router which is 192.168.1.1. But when I boot using the old kernel 2.6.9 everything is working fine. I compared the routing tables and firewall settings, Everything is same between both the kernels. I'm pretty much confused about this. Apparently there is no problem with my network card and I doubt the firewall. Could someone help me with this?
Thanks in advance.
- Jack

Could someone please help with this issue? If there is no solution to this problem then I would like to remove my kernel 2.6.12 and reinstall it. Can someone tell me how to uninstall a particular kernel?
Thanx,
- Jack