I am working on a HP laptop specifically a Pavillion DV6642ca. This is a friends machine and she brought it to me and said it quit. Went to start it and nothing. So I went to the bios ran the HD test, failed bought exact replacement drive, refurbished. HD is fine according to same test. will not load windows 7 or the HP recovery disks (Vista). Set Bios to boot from CD, get "press any key to boot from CD" select. computer runs through cd like it was going to load but never writes to the HD (disk activity light never flickers). Screen says loading windows, four color window shows up and then cd stops computer powers down and reboots. Exact same symptoms and results, multiple times. Load again use F8 select safe mode with prompt. Computer picks up operating system, writes to disk (indicator light flashes, lots) get to select language screen, at next screen select fix my Hard drive errors, fixes three errors(result is 1x0 for each) continue, loades more to about 73%, screen says cannot finish loading in safe mode will continue after reboot. So it reboots and goes back to the first series described. Down loaded a fresh .ISO from windose site ran that off the cd same result. ran it from a USB plug, same result. Load Ubuntu 12.04 no problems no errors, works like a charm 1280 x 800 screen setting. Friend cannot get head into Ubuntu. Wants Win 7. use arconis disk, delete partitions repair disk, repair MBR, format NTFS, activate, try again, same results as described above. Be advised that I have already gone through the HP support advisors and no joy. Sorry for the long story. I am thinking that the "tattooing story" may be true. Any suggestions..... Please!