I have a Mac OS X Yosemite version 10.10.5. Today, some suspicious pop ups started occurring. I noticed them when I was shopping on craigslist. The pop ups would be for similar items from retail stores (ex: searching craigslist music instruments prompted a music instrument retail store pop up.) I have a couple other pop ups related to out of date flash and something regarding my internet provider. I haven't had anything like this happen on this computer before. I ran malwarebytes anti-malware software scan but the issue still remains.
Any help would be appreciated.
For the music store related popup, that could just be a result of cookies.
As to the Flash popup and the ISP popups, can you post screenshots? The ISP one could also be related to cookies. The flash popup could be real or it could just be from a site that gives you fake flash popups to get you to try downloading something on the malicious side.
Do you have Flash installed?
Which browser are you using? Are you using any sort of popup blocking extension? FWIW, Safari has its own built-in popup blocking ability, but it is kind of like a sledge hammer (i.e. it blocks EVERYTHING, even stuff you might want to popup).