For the last few weeks, something is preventing Firefox ESR from launching on a Windows XP laptop (it still works on an XP PC). I am running Malwarebytes Antimalware FREE and AVG Internet Security, among other programs (paid-for Malwarebytes - but currently no AVG - on the PC which works). I can see that there are sessions running in Task Manager, but no windows open. I *occasionally* have a message on shutdown saying something like "nsappshell event window" - not sure whether that's related, although I gather it's Firefox-related. I've also tried installing PortableApps' Firefox ESR app on the laptop in the hope that I might be able to launch that instead, but that doesn't work either. Any suggestions appreciated (and yes, I *am* trying to get a more up-to-date computer!)