We are setting up Zimbra on a Linux box. Centos is running in a KVM on Ubuntu. Installation fails at the ldap initialization.
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host---Ubuntu 10.10 64 bits

vhost---CentOS release 5.6 (Final) 64 bits

zimbra version---Release 7.0.1_GA_3105.RHEL5_64_20110304210645 CentOS5_64 FOSS edition.

logfile point of failure;
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Mon May 2 16:20:41 2011 Initializing ldap...
Mon May 2 16:20:41 2011 *** Running as zimbra user: /opt/zimbra/libexec/zmldapinit
IO::Socket::INET: connect: Connection timed out at /opt/zimbra/libexec/zmldapinit line 136.
Mon May 2 16:21:51 2011 failed. (28160)

According to forum posts it seems that many problems are related to DNS/hosts errors. The /etc/hosts file:
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127.0.0.1 localhost.localdomain localhost
196.168.122.109 zimbra.myserver.net zimbra


dig command reply(dig zimbra.myserver.net MX):
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;; ANSWER SECTION:
zimbra.myserver.net. 86400 IN MX 10 zimbra.myserver.net.

;; AUTHORITY SECTION:
zimbra.myserver.net. 86400 IN NS zimbra.myserver.net.

;; ADDITIONAL SECTION:
zimbra.myserver.net. 86400 IN A 192.168.122.109

best wishes