Even if your record fader in the windows audio mixer isn't muted and is turned to full volume... your soundcard has it's own mixer: I had this problem too, microphone fader was open, I setted everything in the msn options but nothing. When I went to the record settings of my audiocard i found after some clicking a volume-tab, and what did I got? another little mixer just for recording, with stereo-mix, cdplayer, micro, and line, straight from my realtek audiocard software. And for some reason the mic was muted there... but these 4 input meters come together in de microphone fader in windows who wasn't muted at all... however it took me some time to find it. I thought the volumetab would just allow you to set the gain. The software of my card is integrated in the windows interface, not a explicit exe, that's the reason i had to search a bit.I know every pc has it's own software etc but it might help you to search further in the settings... Also some programs mute sound automaticlly and if it crashes it stays that way... good luck