JWS cannot find main class - sometimes

I have a swing application which I've deployed onto several pc's using JWS.
On my PC I can launch the application using the icon which JWS installed and it works properly every time. On the other PC's it will always work the first time it is used after installation, but on subsequent runs it will sometimes works and sometimes fail with an error message suggesting it cannot find the main class.
The error is java.lang.ClassNotFoundException: RichMonV15.Richmon
What I cannot understand is why it will sometimes work, and other times not.
This has me completely stumped, can anyone offer any advice?

The posted JNLP was invalid (I do not know if it is causing the problem, but cannot see how an invalid JNLP would cause the kind of intermittent problem you describe).
Here is a valid form of that JNLP
<?xml version = '1.0' encoding = 'windows-1252'?>
<jnlp spec="1.0+" codebase="http://richmonitor.googlepages.com/" href="RichMonV15.jnlp">
   <information>
      <title>RichMon V15</title>
      <vendor>Richard Wright</vendor>
      <homepage href="http://richmonitor.googlepages.com/downloadrichmonversion15"/>
      <description>Lightweight Database Monitoring Tool</description>
      <icon href="RichMonV1504.gif"/>
      <offline-allowed/>
      <shortcut>
         <desktop/>
         <menu submenu="RichMon"/>
      </shortcut>
   </information>
   <security>
      <all-permissions/>
   </security>
   <resources>
      <j2se version="1.6*" href="http://java.sun.com/products/autodl/j2se"/>
      <jar href="sRichMonV15.jar" main="true" download="eager"/>
   </resources>
   <application-desc main-class="RichMonV15.RichMon"/>
</jnlp>But this could be optimised by removing the codebase from the homepage href, and I am almost sure JNLP files should be UTF-8 encoding. So I recommend you swap that file, for this one (encoded as per stated claims, of course)..
<?xml version = '1.0' encoding = 'UTF-8'?>
<jnlp spec="1.0+" codebase="http://richmonitor.googlepages.com/" href="RichMonV15.jnlp">
   <information>
      <title>RichMon V15</title>
      <vendor>Richard Wright</vendor>
      <homepage href="downloadrichmonversion15"/>
      <description>Lightweight Database Monitoring Tool</description>
      <icon href="RichMonV1504.gif"/>
      <offline-allowed/>
      <shortcut>
         <desktop/>
         <menu submenu="RichMon"/>
      </shortcut>
   </information>
   <security>
      <all-permissions/>
   </security>
   <resources>
      <j2se version="1.6*" href="http://java.sun.com/products/autodl/j2se"/>
      <jar href="sRichMonV15.jar" main="true" download="eager"/>
   </resources>
   <application-desc main-class="RichMonV15.RichMon"/>
</jnlp>

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Why cant it find the main-class?

refer to http://forums.sun.com/thread.jspa?threadID=5314915&tstart=15

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I have seen this error message all over the place but no resolution. I am running Windows XP Pro. I am able to view sites with Javascript such as www.target.com and the dropdown menus work fine. However, when I am using my very very simple Javascript menus (from Project VII) The javascript works FINE on my home PC - but not on my work PC. My Java panel appears to be corrupted, when I try to open it, I just get a blank screen and it hangs. My Javascript is enable in all places.
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you have mentioned about the class "studentList" but that class is not to be found in the code you have pasted. its instead "ListTest". And the "menu" function seems to b a part of "ListTest" class. Can you provide the structure of the classes "studentList" and "Student" so that the problem can be more clearly understood?
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For a beginner these tools are worst, because they
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switching.
Just because an IDE does something for you, it
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Unless you volunteer to handle all "how do I do X in
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questions posted here by newbies yourself.I suppose I can agree with that to some extent. I wouldn't suggest to anyone that they just blindly trust whatever code the IDE inserts automatically.
But there's nothing wrong about learning by example. The IDE is willing to teach proper syntax, and eclipse will give suggestions about capitalizing class names and making constants all-caps.
There are things that frustrate new programmers where an IDE will be helpful, especially if the entire API is uncharted territory.

Servlet cannot find helper class

Hello
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Your example is pretty awful. Try this:
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07/01/2005 03:43 PM    <DIR>          ..
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               3 Dir(s) 74,909,675,520 bytes free
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Hello.....Once you've got your head around this, go learn Ant and have it compile your projects properly.
%

Unable to find main class

Hello
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2. Unable to find main class, Class specified is: oracle/ideimpl/IdeMain
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This is the key piece of information:
I notice that the Install.html document makes a reference to <jdeveloper_root>\jdev\bin\jdev.conf. All the files were unzipped in one directory. There is not a directory structure (ie \bin).
If you unzipped jdev9i_902.zip using WinZip, be sure the "Use Folder Names" option is checked at the time you extract the archive, so that the directory structure will be preserved during extraction. You should be able to verify in WinZip that jdev9i_902.zip does have a directory structure.

Jar file could not find main class.. I cant see why?

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CorePackage\IPEmailer$1.class
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package CorePackage;
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Could not find main class program will exit error while installing Oracle Client 32 bit on windows 7 32 bit OS?

Hi Experts,
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Duplicates of the other two times you asked this question:
https://forums.oracle.com/thread/2559093
https://forums.oracle.com/thread/2558027
(and this time, your question does not appear to have anything to do with this particular forum space, either)
Duplicate is locked.
Do not EVER multi--post. That is extremely bad forum etiquette.

Can't find main class - program will end

Dear forum readers,
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Try this
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Cannot find symbol class Scanner

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you aren't using jdk 5 or higher then. that's when scanner was added to the jdk.
download a modern jdk and you'll be fine.
%

Cannot find symbol class Usernamebean

hi i am new in j2ee
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i am always thankfull to everybody
i have a servlet where i am calling a bean of same package but servlet not compile giving that error
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Hi,
java is case sensitive, Check the case in class name.
Regards,
Ram

"cannot find symbol : class Scanner" error message

I have an error message that says:
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I tried typing at the top of the program
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http://java.sun.com/j2se/1.5.0/docs/api/java/util/Scanner.html
Since:
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look at the javadoc, it says since 1.5 so it's not there in earlier versions.
just a guess

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Message was edited by: Gowsika Kannan

Hi Gowsika,
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Robert
PS: Please do not post the same question 3 times

JWS cannot find main class - sometimes

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