Windows Mail problem, Please Help?

[hooterville]

Everytime I send an email with Windows Mail I get this message:

One or more of the pictures in this message could not be found.
When you send this message these pictures will not be included.
Are you sure you want to send this message?

How in the world can I get Windows Mail to stop giving me this message everytime I send an email?

Thanks.

EDIT: Actually this only happens when I reply to an email received.