Copying files to portable hdd

It's not because of there is limit on ubuntu.
It's because of the filesystem of your hdd which has a limit.

I guess your hdd has a vfat (fat16 or fat32) filesystem.
For a reason I don't know yet, ubuntu cannot copy a file larger than 4GB to a vfat filesystem.

To check out if your hdd is vfat formated.
1. open a terminal (be sure your hdd is on)
2. issue command: "mount"
3. find the line related to your hdd from the output, then you can figure out YES or NOT.(pay attention to the to the words "/dev/... on /...")

To solve.
1. back up everything you need on your hdd
2. open a terminal
3. issue command: "sudo umount /your_hdd_mount_point" (you can see the mount point on the line of the previous step 3, the "/dev/... on /your_hdd_mount_point" )
4. issue command: "sudo mkfs.ext2 /dev/..." (remenber the "/dev/... on /your_hdd_mount_point")
5. issue command: "sudo mount /dev/... /your_hdd_mount_point"

Now, you can have a file with size as big as the free space of your hdd.

Sorry, I have to reopen this.
i am using Ubuntu 12.10
I can't get permission to copy files to USB HDD.
When i enter "mount" it says /dev/sdc2 on /media/fred/Backup type ext4 (rw,nosuid,nodev,uhelper=udisks2)

I tried the chmod 777 /media/fred/Backup and it seemed to go through, as there were no objections or errors, but it still doesn't let me copy the files. I can not decode what's in the brackets.