Send/Receive Button Disappears

I've just installed Outlook 2003 on a brand-new computer. I connect via
Earthlink. My e-mail configuration appears to work when I click on the
"test" option while setting up the e-mail profile. However, when I try to
send or receive, nothing happens. In fact, after the first time I use the
send/receive button, it disappears from the drop down menu. When I compose a
message and click "send" it goes to the outbox and stays there. I've been
using Outlook for many years and have never had this happen.