Hi jjzhuang,
[sorry for delay, I opened the bug topic but when I was writing the forum, I slept 
because time was 3am on Turkey ]
Thanks for your helps but I didn't solve..
I restarted the Zimbra desktop. First, I saw the white opening screen (there are three red icons) during 30 minutes and more.. According to me, the program tried to complete opening but couldn't.
I read your answer which is in the bug topic, but unfortunately I can't think of a reason, too.
thanks..