Two types of problems are most common (try the first one before going on to the second one):

1) the CALCE Java applications require you to have a JRE - Java Runtime Environment.  Depending on the Windows operating system you are using and what vendor your computer was purchased from, you may or may not have a JRE installed on your machine.  A JRE can be downloaded for free from Sun at: http://java.sun.com/downloads/index.html.   This should fix problems running the MOCA and PHM decision support tools).

2) If you are trying to run one of the CALCE Java applications (either MOCA, the PHM decision support tool or the embedded passives cost/size tradeoff analysis tool) on a new PC or an old PC with a recently upgraded operating system, the application may not start-up.  This is especially a problem when running Windows XP, since XP does not ship with a Java Virtual Machine (JVM).  In the case of MOCA, either nothing happens or a black window flashes up and then is gone; in the case of the embedded passives cost/size tradeoff tool you get an error that says:

"Unable to start the application-the Java Virtual Machine cannot be loaded.  Class not registered." 

Microsoft was given a court order to cease providing their Java Virtual Machine (JVM).  Due to this, new Microsoft operating systems are not shipped with any (or at least the correct) JVM.  The JVM you need is named: “msjavx86.exe” and is legally and freely distributed.  Links to download the msjavx86.exe JVM can be found at many places on the web including:

 http://hp.vector.co.jp/authors/VA012735/vm_en.html

Once you have downloaded msjavx86.exe, double click on it to install, and restart your machine.  Your CALCE Java applications should work correctly.

If you are still having problems, please feel free to contact Peter Sandborn.