I have this weird problem with my keyboard, it basically sometimes changes the letters and symbols that are under a tab. It happens all of a sudden, I have no idea how or why. Not sure if that explains the problem here, but it makes what I write: as in what button I press on the keyboard, into something different on my screen.
The only way i found to fix it, is to restart my device.
If that is the case with your laptop, then you are typing something else then what will gets into the post. So what you believe to be an ordinary symbol, is something different when you type.
Am I making myself clear?? I hope it may help you.