Share your experience!
Had the same problem with two M2 phones. Two cards that were used in previous phones died after one week, after showing the same symptoms. Another 2 died after one month. However the next one that I bought is good even after two years, and one of them is now in my XA.
Move my app back from sd card to internal storage help me on this problem. Just use the SD Card to save mp3, photo, video and other file.