Bugs/Lags

Hi guys , I´m playing LoL About 2 Years it´s very good game.Anyway i have an issue with "Match" Searching I Choose "Play , 5v5 Summoner Blind Pick" Then i´m waiting about 5 Mins and then "An uknown problem has occured" "If this lag is reactivating please visit our forums" So guys i´m begging you how can i fix this? I´m going to clean my PC And boost and i will see if was this a problem anyway thank you for response