Sometimes when I'm listening to music, I obviously turn off the screen. But sometimes, (has happened to me twice in the last week), the screen won't turn back on even though the music's still playing. I can't adjust the volume though, and to fix it I have to force reboot it. And even after that, when I turn the screen on, it kind of flickers unnaturally, but usually goes away after a while. Yes, I have an iPod Touch 2G, jailbroken. Any ideas on what's causing the problem?