This is supposed to happen if you put your put your psp in sleep mode while still in an EMU. Soooooo exit the game from now on... dont put your PSP in sleep while in anything.
I ALWAYS put my psp into sleep mode while running homebrew.. my suggestion, just go to the menu of that emu, or just hit HOME and then go to sleep...
EMu keeps accesint MS, so that you may have put it in sleep while accessing.
just make sure htere is no activity before switching it.