I was checking my tank's parameters yesterday and I noticed my ALK, Mg, and Ca levels were all lower than I usually keep them. As I was checking my dosing unit I noticed the screen on my PIII was dark. All the buttons were still illuminated but the screen is dark. I disconnected the power supply, which was very hot, and then plugged the unit in again and it started as normal. Within a minute or so the screen went dark again. Any suggestions ... Thank You in advance for your help, Neil.