Just by looking at the screenshot it appears that your homepage has been hijacked, however it may also be that some sites keep in showing malicious popups with advertising or that kind of deceiving spam.
Have a look at your homepage settings for your browser, and try with a different one if possible.
"Software" isn't the best response agaist security problems, but proper security practices instead. But specifically concerning your actual problem, a popup blocker addin will help, as also the very important ad-locker browser plugins may help greatly here. A very unreliable way of mitigating those is also an antivirus.