First of all, ensure that Opera’s native ad blocker is enabled and try enabling additional lists in Opera settings (Opera menu > Settings > Basic > Block ads > Manage lists…).
It sounds like there is malware or a virus on your computer which is opening unwanted pages in your browser.
Use reputable antivirus and antimalware products to scan and protect your computer. These will need to remove the original malware or virus for you. Without doing this, the other steps listed in this FAQ are essentially useless as the malware can run again and undo all of your fixes. Wikipedia has a good list here: http://en.wikipedia.org/wiki/Comparison_of_antivirus_software.
Note that if you have an existing antivirus product, it may have failed to detect this malware. Try some other products to see if they can detect it.
Once the malware has been removed, either reset your Opera settings (Opera menu > Settings > Browser > Reset Opera) or correct anything it had changed in your Opera settings. For example:
- Are there any unwanted extensions installed in Opera?
Navigate to Opera menu > Extensions. Disable all extensions that are listed, and restart Opera to see if the problem has been fixed. You can now re-enable any extensions you want to keep.
- Has it changed your browser startup settings?
Navigate to Opera menu > Settings > Browser > On startup. “Continue where I left off” is the default setting and should be selected, unless you decide to change it. Also check the “Set pages” link to see if any unwanted pages are listed there (the list is empty by default). Remove any unwanted pages from the list.
- Remove any bookmarks or Speed Dials it might have added.
- Check the properties of the Opera desktop icon which starts Opera. The malware may have added its own address to the end of the command that starts Opera. It may also have done this in your registry.
- Navigate to Opera menu > Settings > Browser > Search > Manage search engines… and remove any unwanted search engines from the Opera settings.
You will need to do this for any other browsers that you have installed as well. If you need assistance with any of this, please take your computer to a local computer servicing centre.