My computer has been lagging recently and I've done everything from CCleaner to working with Belazhur in the Virus section and we cant find the problem. My firefox isn't showing some video's and pages unless I move my mouse.
Can you get me a screenshot of problem ? If you open YouTube and click on some website, do you have BLACK or WHITE page where video suppose to be ? Also, do you have latest version of Flash Player, Mozilla Firefox ? Update your graphic driver may solve your problem.
You just have to download latest version from your product website. If you have NVidia, use link bellow : http://www.nvidia.com/Download/index.aspx?lang=en-us
If your ATI Radeon, check this : http://support.amd.com/us/gpudownload/Pages/index.aspx