My mom keeps taking my black ops for no reason no matter what i do?

Ever since i got cod black ops, my mom has been taking for no reason. I never play it too much, only around an hour a day, 2 hours at most, yet she still takes it. I just finished 7th grade and got a straight A in everyone of my classes; and im not a nerd, therefore effort was actually required to do so. We had to write a 16 page essay (56 paragraphs) and i aced it. Yet for some undisclosed reason, my efforts still leave my mom with spontaneous game-taking. She even tries to take it when im leaving for the whole day, because "She doesnt want me to play." She tells me to go practice guitar or go skateboard, both of which i have been doing so far every day of the summer. I have a given talent, chosen by guitar, so im told i cant take advantage of it so i must practice. And i do... for hours at a time. Yet when my mom comes home from work and sets her eyes on me just starting to play Black Ops, she malevolently screams, "ALL F*****G DAY?!?!?! GET OFF THIS NOW< IM TAKING AWAY FOREVER." That was yesterday, and what she actually didn't know, nor let me have a chance to imprint in her incredibly ignorant brain, that, i made lunch for myself, i went out side for 1 hour, played guitar for 3 hours, went outside again, then got on Black ops minutes before she walked into the house. She can never take the fact that she's wrong, and takes advantage of her parenthood to take my game whenever the hell she wants. I have to hide it all the time so she wont be a total ***** and take it. This morning i set right on a nightstand next to my bed cover it with my sheets so she wouldn't see, but she still came into my room and took it from me, even though she knows im not going to be even at my house for the rest of the day. She really needs to lighten up, and i need advice on getting her not to randomly take my game, she just cant understand that she's completely incorrect on that statement i play it all the time. Its driving me f*****g insane that she is getting her way all the time, i need advice please