Why?!

I promise I don't understand this stupid disease. 

Granny 

1. took her coffee cup with coffee in it and put it in the microwave and turned it on

2. immediately turned around and turned on the teapot for hot water

3. looked in the cabinet and got a coffee cup out

I asked her if she was getting a cup for coffee and she said yes.  I told her that she had just put her cup of coffee in the microwave.  She went and looked in the fridge, then the freezer, and finally the microwave.

I just don't understand.  How can her mind not work even the tiniest bit?!