Outlook 2000 SR1 sends multiple copies of same message.

When I send a message with a large attachment it stays in the outbox and sends multiple times to the recipients who then tend to get slightly annoyed as I clog up their system. I have XP SP2 and use an SMTP connection for outgoing mail. I do NOT have Outlook set to break apart messages.
Any help will be most appreciated.

 

This is what I thought, but the issue did not exist until recently and I have been using the same ISP for about 18 months. The only change in my system is that I had to format the hard drive some weeks ago when an anti-spyware program caused serious things to happen!!

I rebuilt the system and have everything up to date. I will try using my company's ISP to test the idea, but I think the problem is elsewhere. Curiously enough a colleague at work has the same problem, but he uses a diferent ISP to me.

Any ideas you have will be most welcome.

 

I seem to have solved the problem. I am using a Verizon Wireless Card so I can use my companies server for incoming AND outgoing mail. Before I was using Earthlink as my outgoing mail server as they are my DSL provider for my home office. Hopefully this is the final solution. The strange thing is that prior to the reformatting of my laptop I did not have this problem. Anyway thanks for your help.