I have just upgraded to Firefox 15 and after I started using it, I got an error message on my screen saying jar:file:///C:/Program Files (x86)/Mozilla Firefox/omni.ja!/ was not found. I thought that there must have been some error while installing Firefox 15, so I uninstalled it and re-installed it again. But the problem continued to come on my screen. So I had the setup of Firefox 14 which I installed again and the problem was again seen. I mean before upgrading to Firefox 15, the Firefox 14 would work fine. Now even it has stopped working. Can someone tell me what the problem is?