I recently had to have a full system recovery on my pc, so all my software etc. have gone. Now when I open online videos on my pc, the sound is played but the video is just a green screen. It is only green when it is played on Realplayer. I had this problem when i got this pc a year ago, but I forgot how I solved it.
I have looked all over the net, and I can see this is quite a common question, but I don't seem to get any answers.

Could anyone tell me how to get the video to work, as I would really appreciate it.