My friend is trying to use a guest while playing MW3. The problem is once the guest is logged in, his microphone will broadcast through both his primary player and the guest which causes horrendous echoing and skipping. Neither of us can seem to find a way to disable just the guest's microphone, they're either both broadcasting or he just can't use the mic at all.

When he removes the guest the mic works perfectly so I know it's not a hardware issue. Sony said it's a problem with the game itself and not the PSN.