It's just a human verification, happens to me too.
CAPTCHA Code?
The other chess site that starts with and L has chess CAPTCHA's like find the mate in 1 to prove you're human which I thought was clever.
This is a very frustrating thing for me. Chess.com probably just wants humans to comment instead of automated bots typing spam messages to people (or some other reason)
Whenever I tried to send messages, in the bottom right hand corner of the screen, I'll get something that is probably like a CAPTCHA or something, and is a string of weird looking letter and characters I have to put in, like a code. Is this happening to everyone? Does anyone know why?