This is a Windows limitation. There are limits on number of files, file size, number of folders, size of file NAMES, and how the drive is formatted (FAT vs FAT32 vs NTFS). Search Wikipedia for FAT16 (http://en.wikipedia.org/wiki/Fat16#FAT16), and you will find a rather lengthy article on how the file structure in Windows works, some of it rather old, but it is PC history. But, to the point here, put your files in FOLDERS rather than in the root directory of your drive (any drive actually). The root directory has a very small limit of the maximum files that can be placed there, AND long file names makes that limit smaller. If your Cruzer is FAT32 (right-click, properties, look at File System) and your files are over 4GB each, that won't work. Copy the Cruzer files elsewhere and re-format the Cruzer to NTFS, and copy back.