Bug--every text selection event adds another Search with XXX to context menu Rated 4 out of 5 stars

The title says it all, every time I select text, I get an additional "Search with Google" in the context menu (the menu that pops up when I right click on a page). I fixed it by disabling IE8 Activities for Firefox. It might be a bug in combination with another addon (I have heaps), but I'm not sure.