WD My Book Essential 1110, 2tb USB 2.0 is SO SLOW

Try running a test with DLG, if the test completes successfully you might have a data corruption problem, in that case backup all the files you can and then format it. If the test fails, replace it. 

http://wdc.custhelp.com/app/answers/detail/a_id/940/session/L2F2LzEvc25vLzEvdGltZS8xMzQyNjQ4MjQ5L3NpZC9Ja2lMTXQxbA%3D%3D