In USM at tree level the host is shown in green, same as in Details page, everything is green, but in there are alarms in the Alarms tab.
In the CM_DEVICE table there are several entries for the same dev_name with different IP addresses (dev_ip) which means the device's dev_id could be associated with the wrong IP address.
Any Database - Issue related to an alarm produced by the xendesktop probe that connects to the host using its real name while in monitoring it has to use the internal name.
Fixed on any xendesktop 4.0 or later
Deleting all the entries of the dev_name and probe_name in question and restarting the probe the alarm comes from should resolve the issue.