Radio stream has frequent 'rebuffering' with Norton Antivirus 2009

Radio stream has frequent 'rebuffering' when Norton Antivirus 2009 is installed on Vista Home Pro (x64). Both on Itunes and Windows Media.

 

Even with everthing turned off it still seems to cause my rebuffering problem. An XP machine on the same network never rebuffers. This machine rebuffers every few minutes. Using the removal tool eliminates the problem. 

 

Any help much appeciated! 

 

Tom