Since they repaired it, may be they should have another look at their work?
I have an HP Pavilion dv2420 laptop and I recently mailed in my laptop for HP to fix my screen display problems. They replaced my motherboard. Everything was fine until I left my laptop idle for a an hour or two and could not get my laptop out of idle mode; there was just a blank black screen. So I restarted my laptop but it still there was no screen display even though the all the lights on the keyboard were on. I later found out that my laptop would only start up if the ac adapter was NOT plugged in. So then my laptop starts up and I get a loud beep and a screen saying "CMOS checksum bad." My motherboard is new and I bought my AC adapter from Best Buy a month ago. I was wondering what's the source of all these problems ?