Unspecified Error Occurred. Please check board...

This thing happened to me twice over the past week. The first time i fixed it by switching to Oceania (i don't know how that has ANYTHING to do with fixing the error but it helped), and after a week of playing everyday without a problem it happened again. The 2nd time when i logged in the client had a black screen and i couldn't do anything, so i decided to close the client, open it again, and repair it. The repair started and after 10 minutes the message appeared again "Unspecified error occurred. Please check boards..", but this time switching to Oceania was of no help. I tried switching to other regions as well - no result. I tried applying some of the stuff i read in your forums that included deleting the lol_air_client (or something like that) and it couldn't get deleted. I tried various ways to delete that folder (including deleting everything in it 1 by 1 ( some of the things in the folder couldn't be deleted as well)) and i failed. I do not want to re-install the game as last time i did that it did not help and the error was still there (+ it took me like 6 hours to download with the university's wi-fi ). I hope this is specific enough. Please help.