PC can't start with MyBook connected

PC doesn’t boot when MyBook 4.0 is connected. I have to unplug the drive to get the POST screen to come up. Any ideas?

Hi faulknej,

The My Book is formatted with ExFAT by default and is incompatible with some computers when Legacy USB Support and Boot from USB Drive as the first option configured in the BIOS.

You should follow below mentioned link:
https://support.wdc.com/knowledgebase/answer.aspx?ID=15102