[Staffslug] Debian Ports

Hi all, Hope you can help me. I've got quite a long way with Linux over the past few months but I've run into a problem I just don't understand. I've googled it to death but I still don't know enough to resolve the problem. It's Debian Linux and it runs Apache, MySql, PHP and SAMBA at the moment. Everthing works fine. Even the SAMBA shares function as they should and I can access all the shared folders from any windows pc. However, I also need odbc (3306), smtp (25) and pop3 (110) connections from windows machines to work. According to the network tools/port scan the required ports are open. Here is the interesting thing; if I run a portscan as 'localhost' or 127.0.0.1 then ALL the ports are reported as open. If, however, I enter the ipV4 address of this machine and run the scan all the ports I need, apart from 80, are missing. Port 80 appears on both local and lan ip lists. In desperation I re-installed debian Linux from scratch but I got the same results. I then uninstalled iptables but that made no difference either. There must be a configuration file somewhere that needs changing, I just don't know which one. I have already checked host.allowed and hosts.denied, they have no active entries. Hope one of you can point me in the right direction. Very many thanks, Walter