Computer freeze

my computer keeps freezing randomly when I use the internet, sometimes while playing a game like (counter Strike) or most definately freezes almost all the time when playing a video using windows media player. I have tried everything from updating all my drivers to checking for malware, spybot search, antivirus check....nothing seems to fix the issue. I have a pentium D 2.66ghz, 1gb ram, radeon x1300 video card, audigy 2 soundcard