How do I get rid of Fast Browser Search?

My girlfriend somehow got something called “Fast Browser Search” on my computer. It’s something that comes up on Firefox where it works like Google and tries to search for whatever you put in. Now it’s starting to cause problems. I was just in the middle of watching a video online when out of nowhere the video disappeared and I found myself on the Fast Browser Search page, where it was trying to search for the URL I was just on.

This also happened when I hit “Show More” on my facebook home page, etc.

How in the hell do I get rid of this? I went into My Programs and deleted the Fast Browser Search folder, and it’s still here.