Inaccessible Boot Device with Blue Screen

Hi Techs,
I have a Windows 2000 operating system on a Dell OptiPlex GX270 home computer and I am experiencing a problem with starting up. I am getting a blue screen with this error message: 0x0000007B Inaccessible Boot Device
I would like to know how to get rid of this error, as my computer will not boot up completely. I tried running the computer on safe mode, safe mode with networking and the other mode, but still, could not get to load Windows.
I heard from a friend that it could be because of a virus, but how can I scan my system when I cannot even get to my desktop? Please help me.
