For some reason, for the past few months, every now and then when I open Firefox, all of my tabs have been closed, and the only tab that opens is the Bing search page. It's become more regular lately, happening every Monday. I can't use the restore tabs function for some reason, either. Whenever this happens, Bing also becomes my default search engine, and I have to switch it back over to Google. Is there any way to stop this? It's driving me nuts. Thanks!