i have an hp pavilian g6-1d71nr laptop. it worked fine until about a month ago. now when you try to start the system it just says "hard disk 3F0 error, please install an operating system on your hard disk". the error is for a bad sata controller or motherboard. so i took it apart and tried to find any possible loose parts or broken solders or burns on the circuitry. i found nothing. so i temp installed it back together. i didnt screw anything together or have the rear covers on. i loaded ubuntu onto the origional hdd and ran a SMART test. it ran beautifully and booted up about 15 times in a row. then i reinstalled windows 7 onto it. afterwards i tested it using a program called rebooter and made it auto reboot 100 times. it never failed. directly after, i torture tested it to increase heat and stress on the hardware using prime95. i ran it at the harshest setting for 20 mins. nothing glitched or failed. the cpu reached temps of 85C with only the stock coolers. during the test i monitored the temps and voltages using hwmonitor and coretemp, everything seemed fine. right after that i used rebooter again and did another 25 back to back reboots, again everything worked fine. so i figured something was lose or not grounded properly and when i temp installed the hardware i fixed the initial issue. so i put everything back together hoping it would work. first startup, it fails with the same issue. i tried to start it atleast 5 times. then i swapped out the hdd for another one i had laying around with ubuntu loaded on it. first try it works. again i tried that multiple times and it didnt fail. so i put the origional hdd back into the laptop without the rear cover on... and it boots. over and over again just like before. then i install the cover again and it fails everytime. i repeated this process multiple times and 100% of the time it would work when the cover was off and fail when the cover was on. so i came to the conclusion that the curcuit board on the hdd was being improperly grounded or shorting out due to the cover. so i wrap the hdd in ESD tape without the cover on and it fails. it also fails with the cover on. i remove the ESD tape and keep the cover off and it boots multiple times in a row. i then removed the dust shield on the back of the cover hoping that the shield was the issue. ofcoarse it wasnt, i installed the cover without the dust shield and it fails multiple times again. so to my understanding the laptop fails due to the hdd, which doesnt like the rear cover being on. my guess would be due to static or pressure on the drive itself or maybe even a ground. please keep in mind that i did all these tests with the only variable being the cover and the hard drive. i never moved it during the tests, it was always running on battery and yes i checked a/c power as well. if you have any solutions or suggestions, i would much appreciate it. thank you.