In /var/log/samba/log.smb, messages like the following may appear:
[2014/07/03 10:07:31.103652, 1, pid=32974]../source3/smbd/process.c:481(receive_smb_talloc) receive_smb_raw_talloc failed for client ipv4:172.16.101.66:63003 read error =NT_STATUS_CONNECTION_RESET.
This message only says that the opened connection to the client 172.16.101.66 was reset/closed by the client.
You find this string in the /var/log/samba/log.smbd
Without any coincidence of unwished behaviour this is harmless.