can't change homepage per your instructions

I mistakenly downloaded "Bearshare" on the computer and immediately uninstalled it but the next time I opened FireFox, the home page wasn't igoogle as it had been but Bearshare. I found your "easy" means to change the home page, and did so. Hovering over the home icon it showed igoogle, so I closed firefox and returned the next time and guess what, bearshare was the home page. How can I get rid of bearshare?