This started way back in FF 10. For some reason on my main desktop computer I cannot sign into my you tube account. This happen only on this computer. I get no indication of an error, but when I enter my email address and password on the Youtube signon page the you tube home page re-displays with the sign on button instead of my user name. And further onve I've tried to sign on, even though the webpage displays the signon button when I press it nothing seems to happen. I never get the sign on page again. I have to delete all youtube related cookies then I will get the sign on page, but still I can't sign on. I've tried deleting all cookies, I've even uninstalled and re-installed FF, but still I can't fix this problem. I'm running Win7 Ultimate 64 bit. My laptop is running Win7 Pro 64 bit. It does not have this problem, Even my Win8 test machine does not have this problem