Can't enter a game

Everytime I try to play a game, I get kicked out of it and a message comes up: "Resource files not valid. Please exit and restart. Patch will start automatically." Or something like that. Does anybody have any idea what is this? There's no Repair button below Game Start... and I don't feel like re-installing.

redownload or reinstall i think

Enjoy the error then...

Reinstalling is prolly the best solution. It might not even work but do that 1st and if it doesnt work.. then.. w/e xDD