I've also just had a similar problem with signal loss, the base unit also started slowly flashing the green LED, however fortunately I've got a spare Dynamis power supply from another base unit.
Using the second power supply everything worked OK, so plugged the original back in and once again had the same problem.
Next I started turning electrical devices off; Turning an electric lamp off (with an energy saving FLC bulb & electronic dimmer) appears to have fixed it! So I guess its a combination of electronic interference and a power supply that's not tolerant to interference. Guess it might be worth investing in a decent quality power supply sometime.