May be an illustration would help here;
So let's assume this;
Traffic from 172.16.50.2 goes out to internet and it gets translated to 12.105.226.250 because of your 'global (outside)...' statements. When the reply traffic comes back to the PIX, it gets translated back to 172.16.50.3 because of the static you have... So it is going to the wrong host and that is why you're able to have only one host work (that is 172.16.50.3). Hope that helps.
Cheers,
rsivanandan
