blue restart

I have a problem in my windows XP (Service pack 1 & 2). When i try to do one of the following operation , my system being restart automatically: 1)When i try to capture video from a Satellite Reciever or any other devices.(after some minute ...

Hi all,yesterday i downloaded a program with a virus but i didnt have the antivirus installed so windows defender sayed that there are viruses so i installed antivirus(full) and i did a scan but it didnt show any virus.And in 2 minutes the pc ...