NIS 2010 & Media Center Extender

I keep getting disconnected from my Xbox 360 being utilized as a Vista Media Center Extender. Never get music or video unless I run Firefox in full-screen mode, which I saw as a possible bypass from last year's version.  I have spent hours up and down the stairs (Xbox in the attic) trying to get this to work. What do I need to do to get this problem corrected?

 

Date:          2/5/2010 3:45:48 PM
Event ID:      107
Task Category: None
Level:         Error
Keywords:      Classic
User:          N/A
Computer:      SirDave-PC
Description:
An unauthorized window was detected while running the Windows Media Center Experience, 'Norton Internet Security', with file name 'C:\Program Files\Norton Internet Security\Engine\17.5.0.127\ccsvchst.exe'.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="McrMgr" />
    <EventID Qualifiers="0">107</EventID>
    <Level>2</Level>
    <Task>0</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2010-02-05T20:45:48.000Z" />
    <EventRecordID>14996</EventRecordID>
    <Channel>Media Center</Channel>
    <Computer>XXXXXXX-PC</Computer>
    <Security />
  </System>
  <EventData>
    <Data>Norton Internet Security</Data>
    <Data>C:\Program Files\Norton Internet Security\Engine\17.5.0.127\ccsvchst.exe</Data>
  </EventData>
</Event>