My wife is multi-lingual and uses the international keyboard options in the system prefs to access a few different language keyboards. Not a problem on my desktop mac but not so on my rMBP... When I went to wake it up and put in my access code, it refused to accept it - doing a wiggly shake screen thing. My wife (who had just used it) was upset and insisted she had done nothing to it! We finally figured out that she'd had it on another language keyboard and had let it go to sleep. Thankfully she was able to work out where all the relevant keys were and get into it again, but... ...that was only thanks to the fact that the language was 'Latin Character' based. Another of her languages uses Cyrillic. The implications (sickening) slowly dawned on me and I immediately removed that option from the languages in the tool bar. If it had gone to sleep with a Cyrillic keyboard, then whatever we tapped into it would have been unrecognisable by my mbp. My desktop sleeps but I don't use a code to get in, as only family have the use of it, so it's never been a problem until now. Be warned. I have no idea how to get into a mac if this ever happened.