Why does hotmail consider “Name” (email) a typo and not able to send an email

Hi

I run into some problem while managing my contact list. When I compose a new email, certain contacts show up as "Name" (email), while the mailbox is considering "name" a typo and preventing me from sending emails. I tried to delete the "name" portion in the contact list but was resumed to the original format after some time. Not really sure how to fix this.

Thanks in advance!