Right, lets try this, just to test if the problem is Entourage, or something in the OS. ( I Copy and Pasted this from another site)
Test it as a new user to see if the font issue is with your base fonts or if the problem is in your User's folder.
Go to System Preferences --> Create a New User in Accounts. Switch to the
New User by logging out/in or use Fast User Switching. Test Entourage
there. You don't need to enter account info, just test for the problem.
If the problem goes away, then go back to your regular User. Drag your Main Identity to Shared. Switch back to your test User and drag (it actually
copies) you Identity to the Microsoft User Data folder. Be sure to set
Entourage to work offline or set to leave on server under the options tab in
accounts for the test.
If the problem returns with the Identity, then you know it's your database.
If it goes away then your database is good and the problem is in your User's
folder.