I have similar case happen on my friend's computer. But his computer is working on Microsoft Outlook, not OE.
Problem is : He start working on his PC everyday. He can receive mail, but when he want to send any mail, it will shore on outbox and not delivery out until he restart his outlook once.

Tech. department staff try to find out what happen on his mail box from server side. No any solution out.

Until one day, his IE can't veiw some web page. So his want to install ad-ware to remove some spyware from computer. After ad-ware completed scan and remove spyware from his PC. Then his problem solved.

Try to download ad-ware and take a full scan on your PC. Hope this can help you to solve your problem.