I have Compaq desktop computer at my home I am using this computer since nine months. This computer had come with windows 7 operating system installed in it. Everything is working fine with this last night I decide to downgrade my windows 7 to windows XP because my oracle software better run on windows xp. But the problem is that the installation discontinue after the initial display while install thing Windows XP operating system. I get the error message saying that "No hard drive found. Please help me to come out of this problem.