Could the 500 GB drive be formatted FAT32, and the 300 GB formatted NTFS? (Open "My Computer" and right click on the drive and select properties, and there's an item "File System" that should identify this for you.)

FAT32 formatted drives have a max file size of 4 GB -- about 22 minutes of DV video. Perhaps you have files longer than 4 GB on the 300GB drive, and thats the problem trying to copy them to the 500GB drive.

If the 500GB drive *is* FAT32, consider converting the it to NTFS format. I don't recall the details, but this topic comes up every couple months, so you should be able to find a post in this forum that describes converting FAT32 to NTFS (you can convert it without losing any data on the drive...)

If this is an external drive (like a USB drive), then make sure other computers you use it with are compatible with NTFS. Once converted to NTFS, for example, Win95 and Win98 computers probably won't be able to access it. And Mac's can maybe read NTFS, but not write to it?

Tim L