Laptop HDMI TV wall system works then no signal
Win 8 HP envy touchscreen laptop HDMI
Screen duplicated
Running 2013 PowerPoint desktop app
Near end of 15 minute presentation
No signal error appears on TV screens
PowerPoint still running on laptop
Unplug restart plug in, still no signal
2nd laptop , Mac plugged in, no signal. The macs owners says maybe converter box
System owner uses their laptop HDMI an hour later and it works
Is it my machine and if so what is going wrong