HELP! bread that tastes like beer

How clean is the container? Maybe yeast is growing on the sides and then scenting the loaves. Wash with a chlorinated cleanser and rinse, then wipe down with a 5% vinegar solution and let air dry would be a solution if it is the container. Could be you have a rope contamination problem. Keep a cool head and read about it to see if that is the problem. For the time being, switch to plastic bags for new loaves , you can throw them away, and see if the problem persists.

Logically if fermentation is going on with baked loaves, conditions are ripe for yeast or fungi growth: warm, moist and dark. Let loaves cool completely before storing in a cool place. :) Mini Oven

I am by no means an expert, but it seems to me that a explanation could be that you are overproofing/overfermenting the dough and/or undercooking your loaf?
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Here are a few additional tidbits of information that might also help you decide what is going on. I copied them from this very helpful document: http://www.pilmico.com/pilmico/download/TBD-II-14.doc
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*Do not store whole wheat flour in high heat areas for long periods of time. The bran and germ components of whole wheat flour, which contains high levels of unsaturated oil may turn rancid and contribute to undesirable flavors. The higher moisture content of whole wheat flour also cause enzymes to further degrade the whole mix.
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*The fermentation requirements of whole wheat breads are lesser than that of regular flour because of the inherent weaker nature of the former. Whole wheat flour doughs have lesser gas retaining ability and are less cohesive. This is due to the dilution of the gluten by the bran and other components. They also lack tolerance to overfermentation. To improve this tolerance, the baker may use any one or a combination of the following: (a) reduction of sponge flour ratio (b) reduction of fermentation time and/or (c) lowering of the sponge or dough temperature.
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*Bake time is longer and at a lower temperature than white pan bread in order to maximize volume and proper finish.
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From Bread-baking 911 website: http://www.baking911.com/bread/problems.htm
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*Sour flavor, strong yeast odor--> Over-risen bread dough. Incomplete baking. Rising temperature too high so bread rose too quickly(e.g. temperature of the dough during mixing). Not kneading enough. Stop the rising when the dough has doubled in size (use finger-top test). Keep rising temperature at 75 - 85 degrees F.