Unable to change user title or location

[Parma]

I can't change anything under the "Edit Your Details" tab in the User CP. Every time I click down to "Save Changes" box, the following message pops up: You have entered an invalid birthday. I even tried clearing all the details and that message still shows up.

Screenshot

 

[Transfinite]

What are you entering as your birthday?

 

[Parma]

About that - I had only entered the month and date, yet not the year.

That's where the whole problem came from. I had assumed that only entering 2/3rds of it would work here, but it didn't.