Saw this reply elsewhere
Hello xxxxxxxxx,
The prompt you received is a legitimate part of PokerStars' robot player detection and prevention system, known as a CAPTCHA. CAPTCHA is an acronym for "Completely Automated Public Turing Test to tell Computers and Humans Apart".
This system helps ensure that PokerStars is as free of "bots" as we can make it. The system has been designed such that most players will experience a CAPTCHA very rarely so as not to be intrusive upon your game play. The exact criteria for who receives a CAPTCHA and when cannot be divulged.
We ask for your cooperation in completing the CAPTCHA whenever it is presented to you, in order to help protect the integrity and security of our games here on PokerStars. Failure to complete the CAPTCHA when prompted may subject your account to unnecessary further CAPTCHAs or more careful scrutiny of your account.
Good luck in your games, and thank you for playing on PokerStars.
Sincerely,
PokerStars Game Security Team
I dont think this is a good check though because most of the time I am not looking at thte chat tab at all in PS client.