First try this easy fix.
1) Quit Entourage.
2) Move the Microsoft User Data folder to the desktop
3) Open Entourage and it will create a new Microsoft User Data folder with
an empty Main Identity
4) Drag from the MUD folder on the desktop, your Main Identity replacing the
current blank Identity.
~/Documents/Microsoft User Data/Office 2008 Identities/Main Identity
If the problems go away there are some other files in the old MUD you might
want to bring over.
If it doesn't work, let's test in a new User.
1) Drag your Main Identity to the Shared folder
"/Users/Shared"
2) Go to System Preferences --> Create a New User in Accounts. Switch to the
New User by logging out/in or use Fast User Switching.
3) In the new User, open Entourage and let it create a Microsoft User Data
folder.
4) Drag from Shared (it actually copies) you Identity and replace the blank
Main Identity
5) Open Entourage
Does the problem go away? If yes, then your Office install is OK and the
problem is in your User's folder. Test Entourage in a new Identity. This
would eliminate your database as the problem.
For more you can visit:
http://repairentouragedb.blogspot.com/