PSP ingame has no sound and home button does not work

[Kfgus3]

When I'm in a game theres no sound and the home button, volume button and brightness button etc doesnt work.

But when I boot the psp up and while im in xmb theres sound and I can change volume. I recently put cxmb onto my psp and then this happened. My psp is 4.01 m33-2

EDIT: ok so it's the cxmb's problem, removing it made things work again. but what is the problem still, why does cxmb stuff my psp up