Been using Firefox with NatWest online banking Web site for years - now this problem last week : https://www.nwolb.com Screen loads and then pops up prompt "What do you want to do with this file?" - Save ends up with an empty file whose name is a Javascript snippet. File name ( yes, file name, not contents! ) is : javascript__(function(){function i(){if(typeof XMLHttpRequest!='undefined'){return new XMLHttpRequest()}try{return new ActiveXObject(_Msxml2.XMLHTTP_)}catch(e){try{return new ActiveXObj.join(_&_)}function k(a){var b={},d=(a Looks like it is coming from https://chat.nwolb.com - presume Firefox is confused by this JS and getting its knickers in a twist - only started happening last week. NatWest technical support say "functioning as designed - use another browser". ( Have screen shot but "Uploaded image" just sits and spins.... )