I lose sound when i plug headphones in...

ok heres the problem... say im on youtube checking out music vids.. i come across a song that deserves to be play loud.. i plug in my headphones and bam.. the sound goes..!! unplug the headphones and i still got no sound!?!

i've ruled out hardware faults (i think) because i still can get windows sounds through both headphones and speakers...

and its the same weather im using IE, Firefox or flock browsers... and even media player and win amp do the same... to get any sound back i have to close and re-start the browser/program..

HELP please!!! thanks