If someone is using my wireless internet on their own

[naives]

Your browser will only show the pages visited using that browser. So someone using your computer when you are not there.

[Jace]

Sounds like spyware to me, yeah.

Dialers maybe too, if it's mainly porn sites.


Get some scanning utility and try getting spyware/adware/virusses removed.

[weipei]

As far as possible, you should refuse the more clean-up computer files, and view the history, do a good backup encryption (important documents), and optimize the computer.
Good luck ~

[saynews]

somehow you visited the sites or someone else did this.ask others about it. your browser history is only for your computer.