What does the low pressure gauge read? Does it keep going up? How high? It actually sounds more like you have a really bad leak in the keg or maybe you are completely missing the oring on the gas post.
Late reply. Gasket is intact and not cracked. Pressure is normal in the co2 tank. The problem went away on its own, strangely. I have no idea what caused it, but I would like to have figured it out. Only thing that I can think of is that the co2 tank was sitting in the fridge for two weeks after the last keg was spent. Should I have taken it out and let it sit at room temp? It was working fine with the last keg and after two weeks of sitting in the fridge it acted up when I hooked it up to the new keg. The problem went away after taking it out of the fridge for 30 mins or so.
A lot of folks have their CO2 tank and regulator(s) inside their kegerator/keezer and seem to get by. Unless something (like moisture) actually froze inside your regulator, I would look elsewhere for the root cause of the problem. It might be as simple as a bit of machining debris got caught in the regulator seat but eventually cleared itself...