Sites that open when the browser is turned on may appear for various reasons: Sometimes it happens when installing various programs from the Internet that change the settings, because you forgot to refuse it, sometimes it is a malicious software, in this case windows with ads usually appear. Consider all the options. Solutions are suitable for Windows 10, 8.1 and Windows 7 and, in principle, for all major browsers (about Microsoft Edge is not yet sure).
Note: At the end of 2016 - early 2017, the specified problem has a new option: the opening of the windows of the browser is prescribed in the Windows job scheduler and they open even when the browser is not running. About how to correct the situation - in detail in the section about removing advertising manually in the article in the browser pops up advertising (opens in a new tab). But do not hurry to close this article, perhaps the information in it is also useful - it is still relevant.
About solving a problem with the sites opening in the browser (Update 2015-2016)
From the moment this article was written, malicious software was improved, new ways of distribution and work appeared, and therefore it was decided to add the following information to save you time and help with solving the problem in different embodiments today.If at the entrance to Windows, the browser itself opens with the site, like SmartInf.ru, 2inf.net, goinf.ru, Funday24.ru, sometimes it looks like a quick opening of some other site, and then redirecting one of These or similar, then this topic is written on this topic (there is also a video) which will help (I hope) to remove such an opening site - and I recommend starting from an option describing the action with the registry editor.
The second widespread case - you yourself launch the browser, something in it, and new browser windows with advertising and unknown sites can spontaneously open when clicking anywhere in the page or simply when opening a browser automatically opens a new site. In this situation, I recommend to enter as follows: first disable all browser extensions (even trusted to all 100), restart it, if it does not help - check the adwcleaner and (or) MalwareBytes antimalware (even if you have a good antivirus. About these programs And where to download them here), and if it did not help, then more detailed management is available here.
I also recommend reading comments to the relevant articles, they have useful information about who and what action (sometimes not directly described with me) helped get rid of the problem. Yes, and I myself try to update as new information about the correction of such things appears. Well, our finds also share, they can help someone else.
How to remove opening sites when opening a browser automatically (option 1)
The first option will be suitable if there is nothing malicious, any viruses or something like on a computer, and the opening of the left sites is associated with the fact that the browser settings have been changed (this can be done and the usual, right program). As a rule, in such cases you see sites like Ask.com, Mail.Ru or similar, not representing threats. Our task is to return the desired start page.
Correct the problem in Google Chrome
In Google Chrome, click on the settings button on the right and select "Settings" in the menu. Pay attention to the item "Initial Group".
If "the following pages" is selected there, then click "Add" and open a window with a list of sites that open. You can delete them from here, put your website or in the initial group after uninstalling select "Quick Access Page" in order for the Chrome browser opening the pages that you most often come in.
Just in case, I also recommend re-create a browser label, for this: remove the old label from the taskbar, from the desktop or somewhere else. Go to the Program Files folder (x86) \ Google \ Chrome \ Application, click on the chrome.exe right-click and select "Create a shortcut" if there is no such item, just drag chrome.exe to the right place while holding the right (and not The left, as usual) the mouse button when you release it, you will see the proposal to create a shortcut.
Check if incomprehensible sites have ceased to open. If not, we read further.
We remove the opening sites in the operator's browser
If the problem occurred to Opera, correct the settings in it in the same way. Select the "Settings" browser in the main menu and see what is specified in the "when starting" item at the top. If you select "Open a specific page or several pages", click on "Set Pages" and see if the very sites that are opening are not specified. Remove them if necessary, set your page or simply install the usual opera start page at startup.
It is also desirable, as in the case of Google Chrome, re-create a browser label (sometimes these sites are prescribed in it). After that, check whether the problem disappeared.
Second solution solving problem
If the above has not helped, and sites that open when the browser is started have an advertising nature, most likely, malicious programs appeared on your computer, which cause their appearance.
In this case, a solution to the problem described in the article about how to get rid of advertising in the browser, which was discussed at the very beginning of this article. Good luck in getting rid of attack.