Entourage window resizing issue
It's most likely that your Entourage preferences file is corrupted in some fashion. Try this:


Close Entourage. 
Navigate to ~/Library/Preferences/com.microsoft.Entourage.plist.
Move the file to the Desktop. 
Open Entourage, resize the window to your preferred size. Entourage will automatically make a new preferences file. 
Close and open Entourage again to test that the change sticks.


If all is well, you can trash the original com.microsoft.Entourage.plist file from your Desktop.