I believe this is an issue with the way the Windows deals with text files opened with fopen(). If you take a look at the MSDN page for fopen(), it indicates that if you open a file with just "r" as the mode string, some translations will happen with regards to line-endings. This means that the size of the file you query may not match the amount of data read by fread().

To solve this, simply change the mode string to indicate that you wish to read the file as binary data (i.e. without any pesky translations):

FILE* file = fopen(files[i], "rb");