Slowing my pc down

sir/madam,

i had a problem on my wd external drives, i was copyng a movies and the error appears and saying could not the I/O error. the drives is divide in to two cd and storing drives but there is a time that the computer cannot dettect the storing drives it was showing 0 bytes. and make my pc slow.

my drives is My passport Essential SE.

hoping your asap response.

How old is your drive?