This is a problem I've had since windows phone 7.5 on my Samsung Focus. I thought it might be isolated to that phone but I have since had the same issue with windows phone 8 on a Nokia Lumia 920.
Its the headphones.....
I had the same problem with the headphones that came with the phone. I put another pair in and it was okay. Put the others back in, same problem.
**bleep** really, only had them for a month and now in the bin.
Live long and prosper.
2012-12-27 6:51 - edited 2012-12-27 6:52
not sure but some of the Nokia system app updates may fix the problem, there was one released just today for the Accessories settings, check them out here: http://discussions.nokia.com/t5/Pool-of-Knowledge/