(Client) "Unknown Error"; Champion Masteries, Match History, etc, disappearing.

This morning, since I have logged in, I tried going to my profile in the client to see when win of the day is up. Yet, when I got there, the profile was blank. All of my champion masteries have disappeared, shows zero mastery score. The section for ranked is blank as well (I'm unranked, but participated in two 5v5 games, so something still pops up). I go to Champions, all of the mastery data is cleared there as well. Match History shows yet another blank page. Spells is blank as well. After a few moments, a popup appears in the client stating that "An unknown error has occured". This keeps happening randomly for the past week or two, and it will fix itself shortly. I try logging out and logging back in, usually works. This morning it didn't. Granted, now that I'm in the middle of typing this, it has decided to fix itself yet again. Does anyone know why this keeps happening, or how to prevent it? I've yet to try queuing while this is happening, because I'm not certain that it wont affect the game.