Won't read disks at some points

So, a backstory on this. It's my dad's XBox 360, he recently gave to me. It runs a little slow, but perfectly fine. The only issue going on is that when I want to play a certain game, I'll put it in, then it'll just read for a second, then say "open tray" but if I put another game in there, it'll work perfect fine. But the issue isn't that. It's the fact that I can lay it on its side, and it'll start the game, but if I turn it off, it'll do this cycle and it makes me mad so much. If someone could please help me, I'd really appreciate it.