Input/output error, can't delete files or repair permissions - USB drive

I am trying to delete files from an external USB drive, and I get an error "Input/output error" when trying to remove via Terminal. When I try and remove from within the GUI, the files just keep re-appearing.

Does anyone know whats going on? Also, I can't repair the disk permissions on the drive either.

Hardware Overview:

Model Name: Mac mini

Model Identifier: Macmini4,1

Processor Name: Intel Core 2 Duo

Processor Speed: 2.4 GHz

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache: 3 MB

Memory: 8 GB

Bus Speed: 1.07 GHz

Boot ROM Version: MM41.0042.B00

SMC Version (system): 1.65f2

Serial Number (system): xxxxxxxxxxxx

Hardware UUID: 62B7E722-D82E-5838-BA6E-B6AF9F1xxxxxxxxx

Mac-Mini:~ hamels$ df -h

Filesystem Size Used Avail Capacity Mounted on

/dev/disk0s2 298Gi 132Gi 165Gi 45% /

devfs 117Ki 117Ki 0Bi 100% /dev

map -hosts 0Bi 0Bi 0Bi 100% /net

map auto_home 0Bi 0Bi 0Bi 100% /home

/dev/disk1s1 1.8Ti 1.3Ti 537Gi 72% /Volumes/Elements

Thanks,