I have seen several people say they have had problems with Knack, all the Sony guys at IGN have given up playing Knack because of how many times they have had Knack freeze, and how many times they have had to uninstall reinstall... I have not played Kncak nor do I own it. Have not had a single issue with my system, it has never Frozen, never flickered, never anything!
The one complaint I have that has been frustrating is more software than hardware. Whenever I use share on Ea sports games, it logs me out of the server and if I am playing an online mode it kicks me out of the game. Have missed two opportunities on amazing plays to share the video, was really sad!