Boot up issue

[Dangab123]

I have the strangest issue. I also receive 3 long and 4 short beeps, it happens  5 times and then computer boots up. It has an error messages on the screen - unsupported adapter installed and then it shuts down several seconds later. I spent hours on the phone with HP support who told me there was a hardware issue after all unsuccessful diagnostics. I finally decided to go to the local Geek Squad, brought my computer and charger there. The technician plugged it in and it booted up right away. He tried it several times with the same success. When I got home, it was still not working for me. Can this computer be sensitive to the voltage distribution, since this is the only thing that is different between it working in Geek Squad and not working at my house. If so, what is the solution please? Thanks 

[Dangab123]

Quick update, I brought the computer downstairs and plugged it in, it started right away. It appears I am having some sort of electrical problems on the 2nd floor, but all other devices are working fine, including other computers. This is very strane.