I have used Firefox for years, and it worked flawlessly. About a week ago, when I click on a button or link in a web page, it no longer opens a new tab. Instead, a small window briefly pops up and is then snuffed out a second later. Changing the settings to open a new window rather than a new tab has not helped. I have not added any new pop-up blockers or antivirus programs, and I did not change any settings in my current ones. I have tried all of the steps suggested by users in the knowledge base, but without effect. Can you help? If I can't get this fixed, then I have no chance but to switch to another browser, and I don't really want to do that.