I have asked this similar question Computer freezing while watching Flash videos from net two week before. As i mentioned in my previous problem my computer freezes while watching online videos showing 100% cpu usage. I have tried the suggestions given in that query and I have formated my whole computer and installed windows and other softwares (with latest updates) but the problem still presisting. If i watch a video online approximately after one hour my system shows very high cpu usage and when i close my browser cpu usage comes to normal(i tried to watch Cybergeddon but my computer is freezing from start,and also other youtube videos).

Can you tell me whether its an hardware problem? if yes can you give any possible explanation( eg:motherboard problem,over heating etc) because i want to tell those reasons to my computer mechanic.