Another hibernate issue

Hi all, there was/is a discussion about powersave features and options. I do not use it that often, but this week going to work with the train I decided to try it out and hibernated the notebook. It is Dell 5440. After power on all worked fine and it came up from hibernation. When the lock screen asked for password and I pressed some key it went again into hibernation state. The second time I powered on, I was able to unlock he screen and go on with my work. This was reproducable - I tried it twice the same behavior. How can this be debugged? regards