Is It the Whole System or Just One Isolated Thing?

Okay, so, earlier today I tried to download paint.NET. Apparently, I clicked the wrong thing and download some kind of PDFviewer ad thing. After removing the programs that installed on my computer, there's still one problem. My browsers, all three, are all acting funny still. Apparently, Babylon installed on all three despite a pop-up that kept saying they couldn't install. After going through another laboring process of trying to remove the programs, I think I got them all or so I hoped anyway. However, some sites still act very slow, especially one site in particular--Personas for Firefox. Any time I got to this site in Firefox, it doesn't load. I go to it in another browser and it takes forever to load. All of my other sites that I like to visit seem fine though. So, is this the website being funny, which I don't think it is, my browsers being weird, or just my system altogether?

Thanks.