Outlook 2007 doesn't go back to online mode

[splintor]

When I'm disconnected from the network, Outlook switches to
Disconnected. When I restart it, it starts in offline mode, which is
OK.

However, when the network connection is back again, Outlook stays in
Offline mode. Doing a manual Send & Receive retrieves messages, but it
then go back to offline mode, and doesn't retrieve messages
automatically.

Is there a way to tell Outlook 2007 to go back online? I cannot find a
"Work offline" menu item in the file menu.

Thanks,
Splintor