Gmail in Email app shows black box instead of message body

First post, so forgive me if this has been answered, I searched but found nothing.

I have my Gmail account as the default account for the iPhone's Email app. I can send and receive messages fine, but if I open up a received email, below the From, Subject, Date/Time stuff, all I get is a big black box. Sometimes with a tiny blue box in the lower left corner, sometimes not. Nothing I do seems to allow me to get rid of the black box or read the body of the message.

Help!