Problems sending and recieving mail in Outlook 2003

i have some questions first:
1. did it worked before? and when did it stopped working?
2. can you delete the messages in your 'sent box' or are the get stuck there?
3. did you try to delete your account and create it again?
4. did you try to pool your massages with 'outlook express' ? cause maybe your email got stuck because some email that sent to you.
5. did you try to enter your email in 'safe mode'?

I am recieving some of my emails in my sent box not my inox.I am also using Outlook 2003

microsoft outlook 2003 in massage has been sent but incoming massages has not display in inbox so pls help