I recently got a new headset, and the Line-in won't detect the headphones. I've messed around with it a bit, and apparently it detects the microphone just fine. I have tried updating the audio drivers, and really can't come up with anything else that might work. Several months ago I was messing around with the audio, and accidentally deleted one of the listed Playback devices in my Sound control panel. I think this may be my problem, but updating the drivers so far hasn't made the device I deleted show up on the list.
I know for a fact that the headset works, because I've used it with my ipod, and the sound was fine. I've tried other headphones with the laptop, and they aren't being detected either.