Some Gigabytes problems with detecting HDD

You need to indicate which motherboard(s) and hard disks? SATA or IDE interface? I own a Gigabyte motherboard with several WD and Seagate hard disks and I never ran into that issue. Is your comment based on personal experience?

First thank you for your response. I'm working at a company and I work with many PCs with different kindes of motherboards and HDDs, but I encountered this problem on some PCs which their mainboards are Gigabyte (with different HDDs) and I find out that it happens on the PCs which their cases have static electricity and I can just guess that when I turned off PC from the back key, the capacitors on the mainboard release their load, and after some minutes when I turned it on, it doesn't have this problem. But I don't understand the exact result of this fault.

The first thing to try is, with the power off at the rear switch, to jumper the CLR_CMOS pins in the center of the board for a few seconds, remove the jumper, then power up the machine and enter the BIOS (if you get a graphics 'splash csreen, you will need to depress <TAB> to get to the post screen) from the POST screen by depressing <DEL>, cursor to the "Load Optimized Defaults" item, and depress <ENTER> to execute this function; save and exit for a reboot, and, with any luck, problem will cease...

Another thing to be aware of is that, if you have Seagate drives, there are a large number with a firmware problem that will sometimes prevent them from coming on-line, and look like a 'dead' drive:
http://seagate.custkb.com/seagate/crm/selfservice/searc...
Follow their directions carefully; 'flashing' the repair firmware to certain drives which do not require it will render those drives inoperable!

Thank you , but I examined this way and the problem remains!

Who made those cases? It looks like they are not grounded properly or you may have faulty grounds. Did an electrician verify the power outlets to make sure they are properly grounded?