probably disk is full

You have to check if your 500 GB drive is formatted in FAT32 or NTFS. You can know this by opening Computer and right clicking on the drive and choosing Properties. From there, you'll see File System either FAT32 or NTFS.

If it's FAT32, you can't copy more than 4 GB as a single file. You'll need to re-format that hard drive to NTFS. Hope this helps.