Invalid client?!?!!?

LolCAAATS

OKAY!, Since the Halloween patch, my client is giving me the error "Invalid client" Wtf? I uninstalled it COMPLETELY, Then downloaded the NEW client from the download pages just as Saiden said and installed it, and patched and everything and I can open the client. But then once I try to open the game a second time, it gives me the error:

LolCAAATS

Other INFO from my client;

[VERSION]
LatestVersion = 1052
MinimalVersion= 1036
OwnVersion = 5

LolCAAATS

help plz...