Yes I've tested with only one NV6480e card without luck :-\ 
Also, I've tried several nv6480e cards and this didn't fix the problem. 
I haven't any other devices connected...I've also made a fresh installation of WinXP without install any other software..no luck  :'( 
  
I'm wondering if there isn't any hardware compatibilty with these chipsets...What model of MB do you generally use ? 
Having said that, chipset i945 appear in the list of hardware recommendation provided by Avermedia, so...don't sure this is the problem... 
  
Thanks. 
Regards,