[greyeaglem]

Humdity can have a big effect on fudge for reasons I don't (not being a scientist) understand. If you always use the same ingredients and this is an intermittant problem, it might be an occasional equipment fluke. If you are using a candy kettle, I would wonder about the thermostat. Does it happen one day and then not for, say, six days; or is it bad for six days and then fine for awhile? Do you always use the same brand of sugar and is it cane sugar? Cane and beet sugar are not created equal and beet sugar is not generally used for candy making. I used to have problems with sugary fudge until I realized the pan I was using retained heat too long and when I would mix in marshmallow creme, chips and nuts, it would keep cooking and turn sugary. Now I put all that sruff in a bowl and then mix in the cooked part. Problem solved. (I was making essentially the same fudge you are.)