I changed Bethany's site on Friday and went to give her a bolus about 2 hours later and the PDM beeped and displayed "PDM error...call customer service". So while freaking out that my PDM went bad, I called them and only had to reset it (unfortunately I had to change her site again because the PDM was no longer communicating with the one she was wearing). Here's the punchline: I didn't know that my hubby had the microwave on at the time I was administering the bolus. The microwave was about 3-4 feet away. The customer service guy said that this is what most likely interfered with the insulin delivery. So a word to the wise....don't have the microwave on while administering a bolus!