HUD not showing up

In a couple of my games, (one where this glitch happened to me, and the other where it happened to a teammate) The entire HUD, minimap and all, does not appear: No items, no abilities, no ping indicator/clock, etc.. Pressing Tab to pull up the scoreboard does nothing, and the option menu says that the HUD is enabled. Quitting the game and reloading seems to fix it, but who wants to miss the first minute or two of the game due to the game being unplayable otherwise? This may just be an error in the client due to a download failure or something, but I thought I should bring this to Riot's attention just in case.

Also, the games where this has occurred seem to take forever to load, even though it indicates that all players are at 100%