(Question moved from General Discussion to
Security Awareness / Malware Discussion / Home User Assistance)
Offers4u is adware, and may come bundled with software downloads. The people behind this are in India but their website is hosted in the US.
You haven't said which browser you're using when you see the advertisements, but it's likely that every browser you've got on the laptop is affected. You might be able to get rid of this by uninstalling one or more programs and removing one or more add-ons from all your browsers, but this adware program is said to download a number of other programs, all of which you need to get rid of. You will probably need a combination of tools to do the job properly. And no, McAfee won't touch this (or the other downloaded programs) because the official line is that these are borderline. Some people (I can't imagine who) might actually want this stuff on their system.
The general consensus from Mozilla and some other forums is that the best removal guide is one from malwaretips - all his suggested tools are free. Don't ever get suckered into paying for snake-oil removal programs, when there are good ones available for free. (Paid-for technical support, now that's another matter entirely. Let's not go there).
Follow the advice in this guide - http://malwaretips.com/blogs/offers4u-virus-removal and that should do it. Personally I think using more than 2 programs is overkill, and I would go for trying to remove or disable browser add-ons and extensions rather than reset the browser(s), but how much of the advice you want to follow is up to you.