Entourage error message 4362

My Outbox says there's a message there, but when I opened it, it was an old message that had sent days ago. Now when I try to open my Outbox, I get an error message that says "The action could not be completed. An unknown error (4362) has occurred. I have also gotten that message when I try to send and receive now.

Does anyone have any suggestions on how I could fix this? I just want my mail up and running like normal.
Thanks!