Hello, I had a look through our French speaking forums and may have found a solution / explanation for you. Here's the best answer:
This means that you system is no longer on the correct time.
- Enter Setup menu (press F2)
- Load default settings
- Change the time to the actual time (and maybe date too if necessary)
- Exit setup and save changes
Try to restart if the same message appears soon, it means that the battery found on the motherboard is faulty, so you may need to change it, although it does not cost very much.
Hope this helps!