From your description, it sounds to me like ice is forming on the cooling fins.
Try shutting down the machine, let everything warm (few hours) and then re-start. Make sure to set humidity to about 65 or so, which will allow the unit to cycle on and off.
Once that's reached, then slowly lower the humidity setting if you want.
Good luck, I'm on my 3rd machine in 3 months!!
Jerry
July 2008