Originally Posted by RichSz
Edit: If I push the volume down INSTANTLY after locking the screen, it pops back on but if I wait a second before hitting volume down it does nothing. That doesn't sound like what's being described above and I can't imagine what I'm seeing causing a problem.
This is exactly what happens on my phone. I'm completely stock, non-rooted, locked, running 4.0.4 OTA. I have my unlock settings set to "slide". Don't have any unlocker or boot apps installed.
I did multiple test to try to get it to wake from sleep. Held down, pressed rapidly, silmultatneous presses of all buttons on the volume rocker.