I am having a terrible time with my chocolate icing. I use half hi ratio and half butter with about 4 squares of unsweetened chocolate and a dash of salt. I then use food coloring to deepen the color. The last few batches I made, after sitting in the fridge a couple of days have little mold spots in it. Does anybody have a clue what is going on with it. My fridge is at the right temp I am just dumbfounded about this. My white icing does not do this. Help!!!!

Are you sure it's mold?? I'm thinking it's unmixed melted choco - the choco is hardening before it gets mixed into the icing well.
Use powdered UNsweetened cocoa powder. Mix it w/hot water to a thick mud then mix into icing.

We looked at it through a magnifying glass and my husband really felt like it was mold. Thank you for the imput. I think next time I will try powdered cocoa and see what happens.