[dalebleh]

I'm not an expert, but I see a couple of things that could be going on.
It depends on what you have and how the computers are configured.

Are your and your friends computer set to static IP addresses?

What are they?

Also, do you and your friend both have cable modems?

Are the routers 'NAT' routers? (to share an internet connection)

Are there any other computers on either of your nets?

What are their IPs?

If the routers are NAT routers (for internet sharing), are either of your computers set to be in the 'DMZ'? (direct, unfiltered access to the internet)

Let us know....