Wow, I'm sorry for your loss... of beer. I almost suffered a similar fate recently, although it had nothing to do with beer for a comp, especially the NHC!
I never got around to posting about it, but a week ago before tapping a helles that had finished lagering, I swapped out one of my kegerator liquid lines for a longer one (doubled the length to 10 ft), and same time added a spare, clean ball lock liquid side QD (black) before tapping the keg. I hooked up the keg, looked at the QD and thought that the little bit of liquid on top of it was what I just spritzed from my star san squirt bottle.
I went and mowed the lawn, and two hours later came back and decided to peek in there again, just because. I found that beer had been leaking out the QD and collecting on the bottom of my kegerator.
The problem was that when cleaning the spare QD weeks before, I had taken it apart, and then put it back together loosely so it would dry out better. So the QD cap was on but not tightened down with a screw driver.
I only lost about 20 oz beer from the keg, and after tightening the loose cap on the QD just unhooked and removed the several kegs from my kegerator, cleaned out the spilled beer, and then replaced/reattached all kegs.
So my lesson learned is DON'T FORGET to check/tighten my QDs anytime I attach a spare one, before applying gas or beer.