dell xps 400 dxp051

The first thing to do is replace the CR 2032 lithium CMOS back-up cell located on the main board of your computer.  You will find the replacement procedure in the manual found here in the section on Removing and Installing Parts:  XPS 400 Service Manual.  When you replace the cell you will likely need to go to System Setup and turn off the setting for the diskette drive.

After replacing the CMOS back-up cell, try running CHKDSK /r from Safe Mode.  If only the file system has become corrupted this may fix the problem.  Running the repair option from your Windows installation disk may not work if you have kept everything up to date as you should.  Reason for this is that the repair option presumes that your installation disk has the same level of service pack as the installed version on your hard drive.  If you have Windows XP Service Pack 3 on your hard drive and only Service Pack 2 on your installation disk, you will get an error message that the version on the hard drive is newer and the repair cannot be performed.

There is also a Microsoft page outlining how the problem may be fixed, but Microsoft warns that, due to special accounts that may be found on an OEM system, it is possible to permanently corrupt your Windows installation if you use it.  I believe it would be the last resort before concluding it is necessary to re-install Windows.  You will find that page here:  How to Recover from a Corrupted Registry.

What you might want to do is purchase a new hard drive, install your system fresh, and then mount the old drive as a second drive so you can copy your data from that to the new one.  If the hard drive you are using is as old as the computer you may also be experiencing the beginnings of a hard disk failure.  After you have copied the data you want you can preserve the old drive as a back-up.

Media Center is basically Windows XP Professional with some applications tailored toward its special purpose.  The original Media Center installations required separate disks; one that contained the set-up program for the applications and the partitions for Media Center, and a second that was the Windows XP Professional installation disk.  The two disks were later combined to make a single DVD so that the installation procedure was easier to follow.

If you examine the hard drive you will find at least two partitions.  The C: drive is still just the operating system, Windows XP Professional, and you should be able to use the same troubleshooting techniques as you would on a standard installation.  The additional partition is for Media Center use and consists largely of the files that are stored for music and video.

You should be able to begin troubleshooting just as you would a straight installation of Windows XP Professional.  Start the computer, press F8 just as the Dell logo disappears to reach the advanced start-up menu, and choose to start in Safe Mode, Command Prompt Only.  Microsoft's directions on CHKDSK are here:  How to Perform Disk Error Checking in Windows XP.

Be aware if you find that CHKDSK doesn't help, and you decide to use the registry restoration procedure given by Microsoft, you may disable the Media Center function and wind up needing a fresh installation anyway.  I really do think you would be better off replacing the hard drive and copying the files to the new drive.

Your computer will accept any 3.5" SATA drive mechanically, the most popular vendors in the U.S. being Seagate and Western Digital.  You can generally find examples of both of these in any computer store and in many office supply stores.  If you live in the U.S. you can also try www.newegg.com.  Since you are using Windows XP you might want to stay clear of Advanced Format drives.  In general, Windows XP must have a special setup program run on the drive in order to prevent degradation of its performance.  Such a drive should be labeled as such.  Western Digital has a Caviar Blue line that should work well with your machine.

EDIT:  Many examples of acceptable hard drives may be found here:  Internal Desktop Hard Drives sold by Newegg.  Remember; SATA, 3.5".  You need not worry about the interface speed as all the drives are backward compatible with the older computers.

ADDITIONAL:  Instructions for removing and reinstalling your hard drive are found here:  Removing and Installing Parts.  The instructions for the hard drive are about 1/3 of the way down the page, though you can also click the index on "Drives" at the top of the page.

could u give me a link to a new hard drive? thanks