central way/button to turn of keyboard shortcuts?

Lately, when I type things it's often happened that part of what I typed disappeared, without me knowing why or what buttons exactly I pressed. Usually I did 'undo' one or more times, and it would be back. But today I had almost finished an email when it all disappeared except for one 'm', and no amount of 'undo' would bring it back. I suspect it has something to do with keyboard shortcuts.
Going System -> Preferences -> Hardware -> Keyboard shortcuts there's a list. Not sure whether it has to do with that. If it does, is there a central way or button to turn it off? Or someone has an explanation what buttons I likely pressed which made text disappear, and how to either disable that 'feature', or what else I can do to prevent this, besides typing consciously slow?