It was a fake Firefox plugin that did redirections.
Does device manager (right-click My Computer => Properties, to bring up the System Properties applet, shown below, and then click the Hardware tab followed by the Device Manager button) show any item with an exclamation mark?I noticed my speakers aren't working anymore. I unplugged them and plugged them back in and windows pops up saying it found an audio device. But I still don't hear any sound.