Microsoft has released an update "KB976092" for Windows 7 which fixes a data corruption issue for Secure Digital (SD) cards. If you are using Windows 7, you should download and install this update.
You have an NTFS formatted SD card. You use Advanced Direct Memory Access (ADMA) to transfer data between the SD card and a computer that is running Windows 7 system. When you transfer data from the computer to the SD card, the data on the SD card may be corrupted. Additionally, unexpected problems may occur when you try to use the affected data.