I'm having an issue;

since earlier this morning, I was searching on google for music, and all that, and I kept getting popups. I tried closing and reopening internet explorer, and I discovered my homepage was changed. I tried to change it to a bunch of different sites like google, yahoo, msn, and a couple of others, but it wouldn't change. Then I tried going to Internet Explorer>Tools>Internet Options>General, and it still would not let me change it. Then I began to try and block the site popping up. It was completely restricted from my computer, but the homepage remained. Does anyone know how to get it changed?

Thanks for any help.