I wanted to cut a selection with ctrl+x but didn't notice that caps lock was on. What happend was that
1. lyx deleted the selection, and 2. inserted a capital X. Apart from the question whether ctrl+X should be bound to cut I don't think that the present behaviour is desirable. I think that lyx should "swallow" unbound keys. I am not sure whether you agree and how easy this can be fixed... Greets, Ed.