Entourage - Simple script, unexpected behavior

Help please from anyone who has worked with Applescript and Entourage 2004.

The following script opens the selected email message(s). However, in doing so, it disables the next and previous arrows in the message’s toolbar. This doesn’t happen if I manually choose “New Message” from the “Open” menu. I’m wondering if anyone knows why.

tell application "Microsoft Entourage"
	activate
	set theMessages to current messages
	repeat with theMessage in theMessages
		open theMessage
	end repeat
end tell