pavillion 27 xi screen goes blank

I have a Pavillion 27xi.  After running for about 10 minutes, the screen goes blank and the power swtch is unresponsive.  If I disconnect the power, it may come back on, but sometimes has discoloration and flashing lines going horizontally across the screen.  Could it be power supply? It has a APD AC adapter.  I hate to think that the monitor would be bad already.