Arduino Uno 3.3V regulator ain't regulating with Vin of +15Vdc

Thanks for the reply. It is weird since the 3.3V regulator (U2 on the Uno schematic) is fed from the +5Vdc supply. I did not have the USB connected so I'm not sure what caused this. I measured twice to be sure I was on the 3V3 pin. I will attempt to recreate the condition.
-Ru55