You don't need to reload your operating system or format your drive. It sounds like the driver for your cdrom (oakcdrom.sys) has either been deleted or is corrupt. Your hard drive might be failing. The line 6 error of your config.sys file is trying to load your cdrom driver, and since the previous error said the file was bad, then the config.sys can't load the driver. If you have any knowledge of DOS, then you can 1)search the 'net for the file oakcdrom.sys 2)download the file to a floppy disk, 3) boot the laptop to a diskette, and 4) copy the downloaded file from the floppy to the path specified in the error (C:\realmode).Reboot and the computer should boot fine.
If the hard drive IS failing, (which would be indicated by a lot of clicking noises from the hard drive and the hard drive light staying on constantly, NOT flashing) more and more files will become corrupt, so it would be wise to backup your data and replace the hard drive.
BC, September 2005