Basically I got my new computer, installed Windows 7, got all the drivers, got Internet, got Steam, got Mumble.
The thing is, I can hear people in Mumble, but they cannot hear me. When I push my push-to-talk button they can hear echos of themselves or even music I am playing in youtube.
It happens while using the front as well as the rear connections.
And with both, my old (Speedlink Medusa) and my new (Sennheisser PC 360) headset, which were both working fine before.
Also while trying it on a different computer with my two headsets I get the same result, I can hear but not talk.
I have no idea, drivers are updated, there is nothing that could have broken the headsets, …
I am desperate for help.

Got some suggestions already: http://etf2l.org/forum/support/topic-17996/page-1/
Nothing worked.

I've had a bunch of weird issues with several headphones/mics.
This sounds absolutely mad, but have you tried talking into your headphone speakers? It could be that your 'microphone' will pick something up.
I had that problem once and simply couldn't solve it. Had to get a new headset.

_________________
'Belgium, a country with many homos also have a pedophile party as far as i know.' - Violetblood

I had the exact same issue. Turns out I had a broken soundcard.

Its some onboard 7.1 sound. You should expect it to work.
But well, it took them 3 weeks to replace a broken graphicscard, not gonna send it in again.
Will get some soundcard tomorrow, since my old soundcard doesnt fit.

Look around in your sound card's options... there's usually a way to toggle between sending what you hear and what comes in through your microphone. That could be what is causing the problem.

Did you enable Stereo Mix as was suggested in the other thread you linked? That is often the cause of issues with mumble as it associates with the wrong service. 'Cos it's crap.

_________________
"Fire rained from the sky on the day I was born: 10,000 lives I ended before drawing first breath. Do not speak to me of guilt or regret, Jonathan.” - Brayan, The Keepers of the Fire