WD my book essential 2Tb disconnect

Hello,

I have  an external WD my book essential 2Tb on win7.

It worked fine in the beginning, but now it’s having problems:

I can still write data on it, but when i try to access data on it or copy files back to my pc it disconnects after a while and then reconnects, interupting the transfer.

I downloaded the wd data lifeguard diagnostics. when I open the program the smart status is all green. When I run a quick test the following error pops up:

"quick test on drive 2 did not complete!

Status code = 07 (failed read test element), failure checkpoint =105

(unknown test)

smart self-test did not complete on drive 2!"

I can only press the OK button. (The hd doesn’t get disconnected though during the test, like with regular file transfers)

Anybody know what’s wrong?

Thanks

Backup and replace dude