Not really, only to say that it's happened to me several times, and isn't something I've been able to reproduce. It happens infrequently enough that the first

Not really, only to say that it's happened to me several times, and isn't something I've been able to reproduce. It happens infrequently enough that the first handful of times I thought I must have just forgotten to lock the machine. Eventually I realised that wasn't so and I wasn't just imagining it because, of course, by this time I'd become ultra-paranoid about locking the thing. I'm running a ~2 year old Dell XPS equipped with a touchscreen. It's a decent machine for my needs but nothing special or exotic, and certainly I can't see any reason why this would be an issue. I don't know what else to tell you other than I wish I was making it up.