前几日，在浏览网页时，突然 Firefox 自动消失，进而弹出如下的一个窗口：
NOTICE: Your system is not optimized and your computer performance is not at the highest level. Full system optimization will greatly increase your computer’s performance and prevent data loss. Would you like to install HardDriveGuard to optimize your computer’s performance now for free?(Recommended)
确定后会连接到一个 HardDriveGuard.com 的网站，杀毒软件也没报毒，也不确定是不是恶意代码网站，怀疑是某些网站的广告代码触发的，要不怎么能自动弹出呢？
搜了一下，也无结果，看来很少有人遇到。