I recently sent my HP Pavilion Dv7 laptop back to the HP repair service while it was still under warranty due to what I think was a loose connector or cable between the graphics chip and the LCD screen, causing flickering colors when the screen was moved. This would happen at the BIOS, in the bootloader, and in both Windows and GNU/Linux, so I'm confident it was a hardware problem. (This exact problem had happened before, and I had sent it back to be fixed; the problem started happening again several months later and had been getting steadily worse.) Ever helpful, HP again fixed the problem and this time additionally decided to wipe my hard drive to the factory state.
Luckily, I had backed up all my important files, so nothing was lost. It did, however, give me the opportunity to install Debian again, and try to work out some annoyances I had had before.