I have a user whose email are not showing up in her Inbox. She has Outlook 2007 SP2 and we are running Exchange 2003. If she searches her inbox it will find messages that are in the inbox and she can open them. If she logs into webmail everything shows up correctly in her inbox. She will get a bar across the top of the inbox in webmail that says "An error occurred processing your junk mail list. You are over the size limit allowed." Also when she goes to manage the junk email lists in the options for webmail it doesn't load the page. It only displays this message "HTTP/1.1 500 Internal Server Error".
I also logged into two separate machines that she has never logged into before and the same problem occurs in Outlook. One machine was Outlook 2007 and one was Outlook 2003. If Outlook is set to Cached mode if will update all the folders, but when it tries to update the Inbox it will stay on waiting to update this folder.