After looking into this further I checked firewall settings in Panda A.V. For Firefox they were set to Custom settings which effectively disabled it. I changed setting to Outbound only like Internet Explorer and other programs and Firefox seems to work fine now. Hope this helps others who have experienced this problem. I have teenage children who use computer a lot (Face Book, etc.) so the root of the problem may have been Malware, Adware, or something else but hopefully Panda has taken care of this.