When i log into multiplayer servers on vanilla profiles, my screen flickers whit in the top where it says 1.6.4, i am yet to see if it happens on 1.7.2, also i have reinstalled

When i log into multiplayer servers on vanilla profiles, my screen flickers whit in the top where it says 1.6.4, i am yet to see if it happens on 1.7.2, also i have reinstalled it twice and both times it has occurred, no mods are loaded and i have whipped the mine craft folder from my desired location before re-downlaoding it.