We’re surprised by broken Raritan KVM console (Java application) on some of our workstations, mine included. We could login to the Raritan KVM (Dominion KX II), but could not open console to any server. We’re always greeted with the error:
Error while getting the list of open Targets, please try again in a few seconds.
First we upgraded Raritan firmware to the latest one (2.5.0.5.886), but the error was still there. The next suspect was Java itself. I noticed that coworkers working with older version of JRE does not have the problem…and to make long story short, we finally found explanation for new “security feature” introduced in Java 7 U51, a quote from Oracle release notes:

Since Dominion KVM server applet is not signed the JRE will block the app by default. The solution is to add url to Raritan KVM server to the exception list.

First, make sure that you open correct (the latest) Java Control Panel, this is especially important if you happen to have more than one JRE/JDK on your machine, because you won’t find the “Exception Site List” in older Java Control Panel. In my case (Windows7, x64) the best approach is to manually find the executable:

C:\Program Files (x86)\Java\jre7\bin\javacpl.exe

Then check the version:

Add url to exception list: