What causes java.util.zip.ZipException error in opening zip file randomly after application has been running for a while in JBoss EAP 5

Issue

We randomly see 'ZipException: error reading zip file' occur when trying to load a class after an application has been running fine for some time. The class is in a jar which we added via the jboss-service.xml :

<classpath codebase="../../../myapp/lib" archives="my-common-classes.jar"/>

The exception we see is :

 Unexpected error during load of:com.redhat.examples.ExampleObject
java.lang.RuntimeException: Unable to load class byte code com.redhat.examples.ExampleObject
        at org.jboss.classloader.plugins.ClassLoaderUtils.loadByteCode(ClassLoaderUtils.java:155)
        at org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:604)
        at org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:592)
        at java.security.AccessController.doPrivileged(Native Method)
        at org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:591)
        at org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:568)
        at org.jboss.classloader.spi.base.BaseDelegateLoader.loadClass(BaseDelegateLoader.java:135)
        at org.jboss.classloader.spi.filter.FilteredDelegateLoader.loadClass(FilteredDelegateLoader.java:131)
        at org.jboss.classloader.spi.base.ClassLoadingTask$ThreadTask.run(ClassLoadingTask.java:455)
        at org.jboss.classloader.spi.base.ClassLoaderManager.nextTask(ClassLoaderManager.java:267)
        at org.jboss.classloader.spi.base.ClassLoaderManager.process(ClassLoaderManager.java:166)
        at org.jboss.classloader.spi.base.BaseClassLoaderDomain.loadClass(BaseClassLoaderDomain.java:287)
        at org.jboss.classloader.spi.base.BaseClassLoaderDomain.loadClass(BaseClassLoaderDomain.java:1163)
        at org.jboss.classloader.spi.base.BaseClassLoader.loadClassFromDomain(BaseClassLoader.java:862)
        at org.jboss.classloader.spi.base.BaseClassLoader.doLoadClass(BaseClassLoader.java:502)
        at org.jboss.classloader.spi.base.BaseClassLoader.loadClass(BaseClassLoader.java:447)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
        at com.redhat.examples.ExampleBean (ExampleBean.java:123)
        ...
Caused by: java.util.zip.ZipException: error reading zip file
        at java.util.zip.ZipFile.read(Native Method)
        at java.util.zip.ZipFile.access$1400(ZipFile.java:56)
        at java.util.zip.ZipFile$ZipFileInputStream.read(ZipFile.java:679)
        at java.util.zip.ZipFile$ZipFileInflaterInputStream.fill(ZipFile.java:415)
        at java.util.zip.InflaterInputStream.read(InflaterInputStream.java:158)
        at java.io.FilterInputStream.read(FilterInputStream.java:107)
        at org.jboss.virtual.plugins.context.zip.CertificateReaderInputStream.read(CertificateReaderInputStream.java:129)
        at org.jboss.classloader.plugins.ClassLoaderUtils.readBytes(ClassLoaderUtils.java:213)
        at org.jboss.classloader.plugins.ClassLoaderUtils.loadByteCode(ClassLoaderUtils.java:151)
        ... 26 more