Hi, I am using windows 7 64bit and daily I am facing a very strange problem with viewing videos on youtube, gametrailers etc. So, when I start my pc and go to youtube and play any video, it plays. But after 1-2 hours when I again visit youtube or any other site to view videos, it does`nt play, the screen is just black. So then I restart my pc and try to play that video again and then it plays. So to view the video I have to restart my pc, then it plays but if the computer is on for like 2-3 hours and then I try to play video on youtube it does`nt work. Again I have to restart my pc. I don`t know what`s causing this problem. Any help? BTW I am using k-lite codec and firefox and also have installed flash.