I have seen a few threads on adware and Macs, and didn't see any solutions to my problem. I was also overwhelmed by the overlying discussions on Macs and viruses/trojans/malware/adware. I'm sorry if this has been answered elsewhere. There is something wrong with my Mac regarding ads. When using YouTube on Firefox, I receive pop-up like ads that obscure the video I am watching as well as some of the video controls. It is extremely inconvenient and is ruining YT for me. I really don't think I'm just experiencing ads. For one, why would ads be popping up over the product (the video) AND other ads? I can open the ads, but I can't ever pop out of them (without closing the window). Also, this is only happening on Firefox. There's obviously a quick fix to this: change browsers. However, I don't want to just ignore this problem. I understand that adware/malware is extremely rare, and I am reading many posts that say viruses and trojans don't exist. I'm admittedly not computer savvy, and I don't have a great understanding of the differences between trojans/malware/adware/botnets/etc. I'm not making any value statements on Macs susceptibility to viruses and the like. But I have something. I haven't torrented software before, but earlier this summer I did dl an episode of a TV show because I missed part of it when someone came to my door. It took several tries, and I might have enabled a java applet or something, and I think I remember wondering why two files seemed to come up on my computer for a single video. So I already screwed up...I'm guessing that's where I caught whatever this is (I only just now realized that the problem I'm having isn't normal on YT, when I used a friends computer and asked why he didn't have those obnoxious ads covering the other ads). So having already let the problem in, where can I go from here? I tried deleting some plug ins and downloads. I have been using FFMpegx and MacTheRipper without incidient for over 6months, so I don't think these are the problems, but it's possible I absent-mindedly allowed other codecs on my computer. I really can't pinpoint when the trouble started, as it was a few months ago. I tried erasing Mozilla and reinstalling, but that didn't help. Safari has no problem, even after I ran YT with java enabled for a brief test. I'd prefer not to use an ad blocker as the solution because it will just cover up the symptoms and I don't mind well placed ads that don't render a website useless. Thank you for reading the thread. ADDED: I forgot to mention that around when I think this started, someone left a message on my YT account which was flagged as spam.