you get an invalid response, that means one computer can send traffic to the other and the other can respond. The error says the response is not what is expected.
The problem is no longer network problem but samba configuration problem.
You may need to add the other computer name and its IP address in "/etc/hosts" file. This has solve samba problems for others.
that error msg is not very informative, can you repeat with with "-d 3", that will give more verbal output.
The title should be something close to " samba sharing not working". It should atleast mention "samba" and "sharing".
You may loose people who know the problem simply because they will assume it is not a samba sharing problem and may skip your thread.