Roughly 90% of the time I am using firefox to access and export excel files from a site used for the back end of our point of sale system, the tab I am exporting from jumps to a random URL (usually for a utility company I use to pay utility bills through). I have to go back several pages to get back to the original. It is totally problematic, and fairly random and often the utility company URL will vary; sometimes it's the gas company, sometimes it's the power company....occasionally the internet service provider).