External hard drive

I have a external WD drive attached to my pc. When I turn the PC on the computer will stay in the start up screen. If I detach the external before I turn on the PD then the computer will boot up correctly. Any ideas on how to stop this?

This drive working? Did you check smart of it?

The drive does work. It only stops my PC from completely starting if it is plugged in before I start it.

What do you mean by smart drive?