Centre stage

Apparently, it takes twenty years for someone to live in a new language situation to become completely incompetent in their mother-tongue language.  Obviously, you would have to be using only your second language for it to all fall apart. Most ex-pats in Japan lose their ability to spell and I often get tongue-tied and frustrated when the correct English word just will not come.  The weirdest thing, however, is when you are staring at a simple word and its form looks strange and you just can't trust the spelling and start thinking that there is either something wrong with that word or your brain; I've just been searching for an idiom revolving around the word "stage" and after five minutes or so, a kind of panic set in: s.t.a.g.e....is that "stage", does that really say stage? What are those strange five letters and why are they arranged in that order?  It must be correct as there is a whole bunch of idioms using it here.  Fortunately, it all resettled in the grey matter and I calmed down.  Sometimes it doesn't, and I'll be left unhinged for the rest of the day, by a three-letter word.