You need to manually set the IP addresses so they are both in the same subnet, etc., otherwise the systems will automatically assign IP values which does not let the other system see it. If you are sharing the Internet, only do it on one system, and then point gateway on the other system to the IP of the host you have set up.
On each system, go to "run", "CMD", and then in the command window run "ipconfig /all" to display exactly how each system is currently configured. If the IP addresses are in the same range, but the subnet masks are different, then they will not see each other.
Once you have the current IP address of each system, and have one system pointed to the other, then you should be able to ping using the IP address, not the system name. To use the name to ping you may have to set up the lmhost tables on both system so they can resolve the names to IP addresses (AND

, the IP addresses MUST be manually set on both systems so they do not change!).
HTH
David