Come to think of it, during the time that I (thought I) was experiencing the non-responsive physical keyboard, I did ignore a popup that said something about the CTRL key (I think) being stuck or held down or words to that effect, and my daughter also said something similar.
I just checked ease of accessibility, and nothing seems to be out of order -- sticky keys not enabled. Actually, this is the first time that I've given more than a glance at that set of features. Interesting stuff there.
I may have to back off on my claim about the virtual locking out the physical. I just checked remotely and that was not the case, but I am sure about FN/CTRL having the effect described.