Outlook 2003 is erratic

I work on a LAN with 8 other people. We all have XP Pro, SP3.
My Outlook used to download my email as soon as I opened it up, plus send any outgoing as soon as I said “Send”.
Lately, I’ve been getting a lot of Send/Receive errors, and most of the time, I don’t get my first emails for 45 or more minutes when I first open Outlook. Then, throughout the day, I get more send/receive errors and then finally another stream of mail.
I’ve changed nothing and the others in the office are not having the same problem.
PLEASE HELP!!