I have to agree with Drmick above, is your beerline running past anything warm on its way to the tap perhaps?
my understanding is that any significant change in state can stimulate the catastrophic loss of all dissolved gas in a beer, the major 2 culprits are indeed a significant change in temperature, or pressure. The keg fridge should take care of #1 tho pouring into a clean and cold glass could be the solution if your pouring into warm glasses??
whats the serving pressure? and how are you reducing the keg pressure down to a nominal 1-2psi at the tap point?
another often overlooked cause can be a too turbulant flow in the beerline, any kinks or creases in the beerline, and even JG fittings not fully pushed home can be the root, If you cut your beerline with scissors or snips that squeezed the beerline before slicing through you may have concave tube ends due to the deforming, if so this can create neucleation points of turbulance in the beerflow, best to cut beerline with a sharp blade and keep its cut face square ..
Also when was the last time your beer tap nozzels were cleaned? if ignored for a few brews you may have a bottleneck of unwanted gunk/microlife