Recently my HP Pavilion DV7 worked fine, until my AT&T u verse modem went out. Now my laptop will power on, but all I get is a black screen. I tried the "hard reset", no power surges or storms recently and nothing else's was affected besides one of three dvr's in the house. My laptop is closest to the wifi box. Contacted AT&T and they said it's my problem. HP said It's AT&T'S problem. What could be the problem? If it's their problem how can I prove it?