My Tomtom asks for a card while it was installed on the memory card. This has happened before, but after removing the memory card and then re-mounting it, navigation started again. Now the TomTom won't boot anymore, I even formatted the memory card. The card is visible in my PC and I can copy to it and open files, but in MyDrive the card is no longer visible, but the internal memory of the Tomtom (approx 6100 MB) is. The card has functioned for several years.Memory card: Micro SDHC class 10 32GB. What could have happened?