When starting computer new, you can load Firefox okay. After closing it out several times, the icon on desk top will no longer open Firefox......nor will going to programs and clicking on Firefox. The only way you can get it to work again is to reboot the computer, but then you can only bring up Firefox several more times without haviing to reboot. I've even tried to restore computer to previous dates to no avail. If I use Internet Explorer to bring up Firefox the same thing happens. I've tried deleting Firefox and reinstalling, but it tells me that Firefox needs to be closed to continue. I can't see where it is open. Advise