- I had the sound muted
- I double clicked on an MPG file, which launched PowerDVD.
- That infernal program somehow overrode the muting and played the audio anyway.
- I frantically kill the sound because it was muted for a reason.
Later, I went to play Quake 2 and found no sound. I say to myself, "Self, you left the sound muted!" It turns out, though, it's not muted. It turns out, my laptop can't make a peep.
Thinking it has something to do with PowerDVD, I started it up. Lo and behold, it played loud and clear. If I paused it and tried to play something else, that worked too, but if PowerDVD wasn't running, there was no sound.
I went through the online troubleshooting steps (the ones that start with "check your volume") and got nowhere. I tried various steps of starting the player, changing the Windows sound settings, changing PowerDVD's settings, and so on. I rebooted a few times. Nothing seemed to help.
Eventually, after I'd stopped trying to fix it, it just started working again. I have no idea what happened.