Having installed an app and restarted my PC I was met with a message saying that Firefox was around ready running and to close it down. I checked Task manager and it wasn't so I restarted my PC but got the same message again. I uninstalled it and then reinstalled but still I got the same message. I have now noticed that Thunderbird will not load either so now I am stuck. I tried the system restore point but that didnt help and now I do not know what to do. How can I reinstall FF again?