I have this effect, but only with one single app. Right after booting, the generic icon sits there, and if I start using any app (or any functionality), it remains that way all the way through the next reboot. But if I wait another 15 sec or so, all the icons go out for 3-4 seconds, and then when they reappear, all of them display properly (and it then remains that way until the next boot).
No other problem here, though, except that one icon.