I go to bed one night and everything is just fine.  I sleep like a baby all night long with no waking up whatsoever.    

Next night, I go to bed.  All settings are exactly as they were the night before.  Water level in humidifier is exactly the same.  Nothing is different.  Except on this night, I am awakened four or five times by cold air that seems to be blasting into my nostrils.  I have to turn the unit off and then on again so it can begin the ramping process at a lower level and I can get back to sleep.  When it ramps up, it then wakes me up again.  

What's the deal?  I am using nasal pillows which work just fine for me when the unit isn't blasting air into my nose.  Some nights this happens, other nights it doesn't - settings the same every night.

I am wondering if anyone else has experienced something like this and what, if anything, can be done to level things off so that all my nights are the same - acceptable.