Missing Operating System error

I have an HP omnibook Laptop. I turn on the Laptop after succesfully using it before and the error came up missing OS. When I check the BIOS the laptop was not recognizing the hard drive. The only way I could get the systenm to work is to remove all power source ( battery and AC) then it recoqnizes the hard drive and boot up succesfully. This is happening quiet often, which is very annoying. What do you guys think is the problem, could it be the HDD going bad?