[ILUG-BOM] Network problem

There is an odd problem I am facing. I just realized that I can't ping anyone on the network...not even myself (localhost). :-s

I am using two IP addresses in the form of eth0 and eth0:1 . The eth0 is used for Sify's static IP and eth0:1 for the local network. Amazingly, everything including all internet applications and DC work perfectly. But neither can I ping anyone's IP on the local network (except for Sify's server) nor can others ping my IP. The point is that this is happening only on Ubuntu. These things seem to be on m$. Due to this problem, I can't use applications like vnc and gnump3d.

What could be the problem? I have inserted lines for eth0:1 manually in the /etc/network/interfaces

-- Regards, Sanket Medhi.