I posted my code here, please help
Basically, I write_file() something into a file (sd\hello.txt). i can read_file() the same file to get its contents.
But then after I restart, read_file() reads . It seems that everything has been wiped out of the sd card.
I put Thread.Sleep(15000); between FlushAll() and UnmountFileSystem(). Still the same phenomenon.
sorry for the code on tinyclr.com, i will clean it up once the problem is solved :-[