Recently Microsoft has released an Update for Windows 7 to fix a data corruption issue for Secure Digital (SD) Cards. Please download and update your system with this update KB976092.
Issues that this update fixes
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.
Download
x86-based versions of Windows 7 | x64-based versions of Windows 7