I've got the same 3 alternating red symbols as some others, I'm on Windows 7 ultimate 64 bit, and this is the log:

0 INFO [main] log - Logging to org.slf4j.impl.Log4jLoggerAdapter(org.mortbay.log) via org.mortbay.log.Slf4jLog
936 INFO [main] log - jetty-6.1.5
1747 INFO [main] log - No Transaction manager found - if your webapp requires one, please configure one.
Zimbra server process is running as uid=-1 euid=-1 gid=-1 egid=-1
7629 INFO [main] security - keystore not present
failed sending ui_load_event
java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(Unknown Source)

Any ideas? It worked for a while, then nothing...