Macbook wont recognize internal hard drive

I have a polycarbonate A1181 macbook that gives me the question mark symbol during initial boot. If I remove the hard drive from the unit and boot up via USB, it boots up fine. I've tried using disk utilities to try and correct the problem from there with no luck. It seems like while the hard drive in in the macbook, it's not powering up.

any ideas?

Several things to look at:

If the drive will work when it's attached via USB then it's OK. Do this:

Remove the hard drive and look carefully at the slot it came out of. Look for the rubber insulators that fit on the inside of the hard drive cavity to make sure they have not come out of place or are missing. If either one of them (there are two, one for each side) is out of place the drive will not line up and make proper contact with the ribbon connector.

If the insulators are in place and the drive lines up OK to the ribbon connector, then it could be the ribbon cable itself that's bad. The cable extends to the logic board and attaches to a connector on the board. You may have to replace the cable.

You can find directions for replacing the cable at iFixit: The free repair manual. They may also sell the cable if it's in stock.

Thanks, I'll give a try. Just hope it's not the logic board itself.