Kedji Asked: PSP keeps detecting UMD door has opened but its not?

I have a PSP 2000 (Slim), and when I play some games in my PSP, it shows up the place when you click the HOME button. (Do you want to quit the game? Y/N). That always shows up whenever I play. At first, I thought it was my buttons because when I click on one of the arrows it pops up. But later on I discovered that it was my UMD Door that pops the home up.

Now, I have to open the UMD door so that the home doesn't show up anymore.

I haven't done anything with my PSP besides installing custom firmwares and stuff, nothing done to the hardware. I never dropped my PSP and I'm not a gamer who throws my psp if I lose a game or something.

What's wrong with it and how do I fix it?