Description of problem:
In JBoss Operations Network 3.0.0.GA, cleanly installed on PostgreSQL 9.1, when I go to the "Administration" tab and select the "Roles" entry, I get the error: "Failed to fetch roles":

java.lang.RuntimeException:[1323780300911] javax.ejb.EJBException:java.lang.IllegalArgumentException: PageList was passed an empty collection but 'totalSize' was 2, PageControl[firstRow=25, size=50] -> java.lang.IllegalArgumentException:PageList was passed an empty collection but 'totalSize' was 2, PageControl[firstRow=25, size=50]
--- STACK TRACE FOLLOWS ---
[1323780300911] javax.ejb.EJBException:java.lang.IllegalArgumentException: PageList was passed an empty collection but 'totalSize' was 2, PageControl[firstRow=25, size=50] -> java.lang.IllegalArgumentException:PageList was passed an empty collection but 'totalSize' was 2, PageControl[firstRow=25, size=50]
   at Unknown.java_lang_RuntimeException_$RuntimeException__Ljava_lang_RuntimeException_2Ljava_lang_RuntimeException_2(Unknown source:0)
   at Unknown.com_google_gwt_user_client_rpc_core_java_lang_RuntimeException_1FieldSerializer_instantiate__Lcom_google_gwt_user_client_rpc_SerializationStreamReader_2Ljava_lang_RuntimeException_2(Unknown source:0)
   at Unknown.com_google_gwt_user_client_rpc_impl_SerializerBase$MethodMap_$instantiate__Lcom_google_gwt_user_client_rpc_impl_SerializerBase$MethodMap_2Lcom_google_gwt_user_client_rpc_SerializationStreamReader_2Ljava_lang_String_2Ljava_lang_Object_2(Unknown source:0)
   at Unknown.com_google_gwt_user_client_rpc_impl_SerializerBase_$instantiate__Lcom_google_gwt_user_client_rpc_impl_SerializerBase_2Lcom_google_gwt_user_client_rpc_SerializationStreamReader_2Ljava_lang_String_2Ljava_lang_Object_2(Unknown source:0)
   at Unknown.com_google_gwt_user_client_rpc_impl_AbstractSerializationStreamReader_$readObject__Lcom_google_gwt_user_client_rpc_impl_AbstractSerializationStreamReader_2Ljava_lang_Object_2(Unknown source:0)
   at Unknown.com_google_gwt_user_client_rpc_impl_RequestCallbackAdapter_$onResponseReceived__Lcom_google_gwt_user_client_rpc_impl_RequestCallbackAdapter_2Lcom_google_gwt_http_client_Request_2Lcom_google_gwt_http_client_Response_2V(Unknown source:0)
   at Unknown.org_rhq_enterprise_gui_coregui_client_util_rpc_TrackingRequestCallback_onResponseReceived__Lcom_google_gwt_http_client_Request_2Lcom_google_gwt_http_client_Response_2V(Unknown source:0)
   at Unknown.com_google_gwt_http_client_Request_$fireOnResponseReceived__Lcom_google_gwt_http_client_Request_2Lcom_google_gwt_http_client_RequestCallback_2V(Unknown source:0)
   at Unknown.com_google_gwt_http_client_RequestBuilder$1_onReadyStateChange__Lcom_google_gwt_xhr_client_XMLHttpRequest_2V(Unknown source:0)
   at Unknown.anonymous(Unknown source:0)
   at Unknown.com_google_gwt_core_client_impl_Impl_entry0__Ljava_lang_Object_2Ljava_lang_Object_2Ljava_lang_Object_2Ljava_lang_Object_2(Unknown source:0)
   at Unknown.anonymous(Unknown source:0)
   at Unknown.anonymous(Unknown source:0)


Version-Release number of selected component (if applicable):
- JBoss Operations Network 3.0.0.GA
- OpenJDK 1.6.0_22 (fedora-60.1.10.4.fc16-x86_64)
- Fedora 16 X86_64
- Mozilla Firefox 8.0
- PostgreSQL 9.1: postgresql-server-9.1.1-1.fc16.x86_64

How reproducible:
Use Mozilla Firefox 8.0 to select the "Administration - Roles" screen.

Steps to Reproduce:
1. Install JON 3.0.0.GA
2. Open JON Web-console using Mozilla Firefox 8.0
3. Select "Administration" tab.
4. Click on "Roles".
  
Actual results:
Error is displayed: "Failed to fetch roles". Roles are not displayed

Expected results:
Roles are displayed.

Additional info:
- When you click on "Roles" the second time, the roles are displayed correctly.
- This behaviour can be seen as well when using Opera.
- When I use the Google Chrome browser, the error does not occur and roles are displayed correctly.