Java SE (Java Platform, Standard Edition)

Hi there,
I wrote an application including the JAF and Java Mail API (written with Borland JBuilder 8).
With the help of the Native Executable Builder (or what is it called? ;) ) I made a windows exe and a .jar file.
But when I want to start it now it throws the following expection:

Exception in thread "main" java.lang.SecurityException: no manifiest section for
signature file entry javax/mail/internet/AsciiOutputStream.class
at sun.security.util.SignatureFileVerifier.verifySection(SignatureFileVe
rifier.java:260)
at sun.security.util.SignatureFileVerifier.process(SignatureFileVerifier
.java:172)
at java.util.jar.JarVerifier.processEntry(JarVerifier.java:239)
at java.util.jar.JarVerifier.update(JarVerifier.java:194)
at java.util.jar.JarFile.initializeVerifier(JarFile.java:251)
at java.util.jar.JarFile.getInputStream(JarFile.java:313)
at sun.misc.URLClassPath$5.getInputStream(URLClassPath.java:617)
at sun.misc.Resource.getBytes(Resource.java:57)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:247)
at java.net.URLClassLoader.access$100(URLClassLoader.java:54)
at java.net.URLClassLoader$1.run(URLClassLoader.java:193)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:186)
at java.lang.ClassLoader.loadClass(ClassLoader.java:299)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:265)
at java.lang.ClassLoader.loadClass(ClassLoader.java:255)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:315)

I checked if there was a manifest included - and it is (with the correct main class).
I do not know what do do right now - it musst be something with the including JAF or Mail API because it works if I don�t include them (but it has to...).

Hopefully someone can help me out - it was very kind of you!