When Did This Start?
You've left out some relevant information.. Which operating system? Vista? Did the problem recently start with the addition on the new system or did the computer correctly connect originally? Do all the other computers on the network connect correctly?
As to Outlook, are you SURE you've got the settings correct? (Specially the CHECK mark usually required in the "This server requires a secure connection (SSL)" in the POP3 settings page. See [url=]THIS LINK[/url for the basic setup instructions which are similar in Outlook Express or Outlook.)
And what comes to mind here, IF the computer is Vista, have you updated the router and modem firmware with software that has Vista support?
Disabled the firewalls in the router and modem (if it has one) as well?
And just for kicks, if you haven't, please download, install, update using the manual updater below, then run the free Malwarebytes program using the direct download links from the links below:
Malwarebytes Installer Download Link (Clicking on the links below will immediately start the download dialogue window.)
Malwarebytes Manual Updater link
Hope this helps and let us know more.