My productivity is dying for want of a second monitor. I've been hooking up a new-ish HP external LCD to my brand new HP Spectre laptop. Every time I do this, the laptop soon locks up. Won't launch programs, won't even let me click the Windows button to restart. Have to hard reset and go back to single 15" screen. THEY'RE THE SAME BRAND?! WHY ARENT THEY COMPATIBLE?!