Refreshing Firefox didn't fix the problem. Maybe it's some type of annoyance I'm just going to have to live with. I checked it again this morning before coming here to post a response. Just perusing through eBay search results, clicking on links I'm interested from my search, looking at the links, closing links, perusing some more, clicking links, looking at them closing links and then, all of a sudden, another tab opens up with a listing I did NOT click on. I still think that this is some type of exploit being taken advantage of in Firefox settings, some kind of "delayed" opening of embedded links from a previously clicked link. But, I have no way of proving anything like that. I don't know.