My firefox taking homepage http://meta-finder.com/ by default by choice. I can't change it to google.com. Why?

I am using windows 7. Whenever I am changing home page in firefox it is opening it, but once I restart it agin opening up http://meta-finder.com/. I have tried add-on to block this site, but it blocks also google.com automatically. In short I have nothing to accept homepage http://meta-finder.com/. Please help me how to get rid of it?