Terri, if by FACTORY Defaults you mean that you have done a restore of the operating system then it seems as though you have a hardware fault (please though make sure that you have done both a reset of the bios and a full restore before discounting the software and/or settings)
As I said in my original post in the thread if it is a hardware fault then cleaning the drive or a swap-out is really the only two things as an end user you can do. You can take it to a professional (not one of these home support persons who think that as they've stripped a machine down that they're professionally qualified, you know the type
) but without the manufacturers test and set-up equipment (only found at a registered warranty agent and even then they'd probably just send it back to the factory) it's hard for anyone to actually component fix.
Give it a clean up using a wet lens cleaning disk and if that doesn't cure the problem then you've probably got a partial failure of the drive itself. (sorry to say but currently I don't think there's any on ebay)
I'll call up my old workshop and see who they currently use for trade 2nd user Sony bits and see if they have any available
In the mean time I presume it's not under warranty???