I use Windows 8.1, updated. I run Malware Bytes Pro and Windows Defender. When I go to some websites (Amazon, etc) with Firefox (updated), Malware Bytes says that it has blacked a malicious websites - 188.8.131.52 and 184.108.40.206. Sometimes on IE (current) I can tell that it is trying to connect to something else, but it is being prevented from doing that.
Even on this website, when I went to register, it took me to another webpage. I closed that and got back to the registration page.
On a lot of web pages when I'm using Firefox, after the page loads, the big green arrow moves up to the download arrow in the upper right corner, as if it is downloading something, but nothing new is in the folder where Firefox automatically puts downloads.
I ran a full scan with Malware bytes and it removed 46 things. I ran complete scans with Windows Defender and Microsoft Safety Scanner - they found no problem. I ran Malware Bytes again and it didn't find anything.
I'm also getting suspicious popups, for example, a jiggling popup saying "browser extension available" pop up in Firefox.
I uninstalled Firefox and did a clean install. So far I haven't gotten the Malware Bytes message about trying to connect to malicious websites, but in the tab in the upper left it flashes several times, back and fourth between the website I want and something else I can't read (too fast). So it appears to be trying to connect to something else. I updated Firefox and Thunderbird 3 days ago and the problem started after that.
Some sort of malicious software has gotten on my system, and I can't get rid of it. Any ideas?