Config/System File

I have a Dimension 4600 with Windows XP.

There is an error message that the \Windows\System32\config\system file is corrupt or missing. I've tried to copy document files to a disk but can't get the system to copy from c: drivce to disk. Also, the drive won't open now and has the re-installation disk still in it.

Any suggestions as to how to get the drive to open? Can I copy the system file from a XP laptop onto the desktop to recreate the missing/corrupt file?