Christopher,

Can you try running firefox from a terminal and see if you get something like this on the terminal while running the applet?

java version "1.6.0_18"
OpenJDK Runtime Environment (IcedTea6 1.8pre) (6b18~pre3-0ubuntu1)
OpenJDK 64-Bit Server VM (build 16.0-b13, mixed mode)
Looking for 0x7f0160ca84d8 0x7f0160c06300 0x7f017294c8a4 (document)
java.security.ProviderException: Could not initialize NSS
	at sun.security.pkcs11.SunPKCS11.<init>(SunPKCS11.java:201)
	at sun.security.pkcs11.SunPKCS11.<init>(SunPKCS11.java:103)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
	at sun.security.jca.ProviderConfig$3.run(ProviderConfig.java:262)
	at sun.security.jca.ProviderConfig$3.run(ProviderConfig.java:244)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.security.jca.ProviderConfig.doLoadProvider(ProviderConfig.java:244)
	at sun.security.jca.ProviderConfig.getProvider(ProviderConfig.java:224)
	at sun.security.jca.ProviderList.getProvider(ProviderList.java:232)
	at sun.security.jca.ProviderList.getService(ProviderList.java:330)
	at sun.security.jca.GetInstance.getInstance(GetInstance.java:157)
	at java.security.Security.getImpl(Security.java:696)
	at java.security.AlgorithmParameters.getInstance(AlgorithmParameters.java:130)
	at sun.security.x509.AlgorithmId.decodeParams(AlgorithmId.java:121)
	at sun.security.x509.AlgorithmId.<init>(AlgorithmId.java:114)
	at sun.security.x509.AlgorithmId.parse(AlgorithmId.java:381)
	at sun.security.x509.X509Key.parse(X509Key.java:168)
	at sun.security.x509.CertificateX509Key.<init>(CertificateX509Key.java:75)
	at sun.security.x509.X509CertInfo.parse(X509CertInfo.java:705)
	at sun.security.x509.X509CertInfo.<init>(X509CertInfo.java:169)
	at sun.security.x509.X509CertImpl.parse(X509CertImpl.java:1747)
	at sun.security.x509.X509CertImpl.<init>(X509CertImpl.java:196)
	at sun.security.provider.X509Factory.engineGenerateCertificate(X509Factory.java:107)
	at java.security.cert.CertificateFactory.generateCertificate(CertificateFactory.java:322)
	at sun.security.provider.JavaKeyStore.engineLoad(JavaKeyStore.java:763)
	at sun.security.provider.JavaKeyStore$JKS.engineLoad(JavaKeyStore.java:55)
	at java.security.KeyStore.load(KeyStore.java:1201)
	at sun.security.ssl.TrustManagerFactoryImpl.getCacertsKeyStore(TrustManagerFactoryImpl.java:221)
	at sun.security.ssl.TrustManagerFactoryImpl.engineInit(TrustManagerFactoryImpl.java:51)
	at javax.net.ssl.TrustManagerFactory.init(TrustManagerFactory.java:247)
	at net.sourceforge.jnlp.security.VariableX509TrustManager.<init>(VariableX509TrustManager.java:100)
	at net.sourceforge.jnlp.security.VariableX509TrustManager.getInstance(VariableX509TrustManager.java:282)
	at sun.applet.PluginMain.init(PluginMain.java:217)
	at sun.applet.PluginMain.<init>(PluginMain.java:147)
	at sun.applet.PluginMain.main(PluginMain.java:116)
Caused by: java.io.IOException: /usr/lib/firefox-3.6/libnssutil3.so: version `NSSUTIL_3.12.5' not found (required by /usr/lib/libnss3.so)
	at sun.security.pkcs11.Secmod.nssLoadLibrary(Native Method)
	at sun.security.pkcs11.Secmod.initialize(Secmod.java:203)
	at sun.security.pkcs11.SunPKCS11.<init>(SunPKCS11.java:197)
	... 37 more
java.lang.InterruptedException: sleep interrupted
	at java.lang.Thread.sleep(Native Method)
	at sun.applet.PluginAppletViewer.handleMessage(PluginAppletViewer.java:629)
	at sun.applet.PluginStreamHandler.handleMessage(PluginStreamHandler.java:270)
	at sun.applet.PluginMessageHandlerWorker.run(PluginMessageHandlerWorker.java:82)
java.lang.InterruptedException: sleep interrupted
	at java.lang.Thread.sleep(Native Method)
	at sun.applet.PluginAppletViewer.handleMessage(PluginAppletViewer.java:674)
	at sun.applet.PluginAppletViewer.handleMessage(PluginAppletViewer.java:649)
	at sun.applet.PluginStreamHandler.handleMessage(PluginStreamHandler.java:270)
	at sun.applet.PluginMessageHandlerWorker.run(PluginMessageHandlerWorker.java:82)
java.lang.InterruptedException: sleep interrupted
	at java.lang.Thread.sleep(Native Method)
	at sun.applet.PluginAppletViewer.handleMessage(PluginAppletViewer.java:735)
	at sun.applet.PluginAppletViewer.handleMessage(PluginAppletViewer.java:649)
	at sun.applet.PluginStreamHandler.handleMessage(PluginStreamHandler.java:270)
	at sun.applet.PluginMessageHandlerWorker.run(PluginMessageHandlerWorker.java:82)
java.lang.ArrayIndexOutOfBoundsException: 5
	at sun.applet.PluginProxyInfoRequest.parseReturn(PluginProxyInfoRequest.java:65)
	at sun.applet.PluginStreamHandler.finishCallRequest(PluginStreamHandler.java:338)
	at sun.applet.PluginStreamHandler.handlePluginMessage(PluginStreamHandler.java:287)
	at sun.applet.PluginStreamHandler.handleMessage(PluginStreamHandler.java:208)
	at sun.applet.PluginMessageHandlerWorker.run(PluginMessageHandlerWorker.java:82)
java.lang.ArrayIndexOutOfBoundsException: 5
	at sun.applet.PluginProxyInfoRequest.parseReturn(PluginProxyInfoRequest.java:65)
	at sun.applet.PluginStreamHandler.finishCallRequest(PluginStreamHandler.java:338)
	at sun.applet.PluginStreamHandler.handlePluginMessage(PluginStreamHandler.java:287)
	at sun.applet.PluginStreamHandler.handleMessage(PluginStreamHandler.java:208)
	at sun.applet.PluginMessageHandlerWorker.run(PluginMessageHandlerWorker.java:82)
** Unimplemented: IcedTeaScriptableJavaObject::invalidate 0x7f016147a0d0
** Unimplemented: IcedTeaScriptableJavaObject::deAllocate 0x7f016147a0d0