Help on file is missing or corrupt error

My laptop specs:
Model: Sony Vaio Y Series 2011
Operating System: Windows XP Professional(The original OS is Windows 7 Starter Edition but I decided to change it to Windows XP because it's for me its easier to use)
Processor: AMD Dual Core Processor E-350 1.60GHz
RAM: 2Gb DDR3 SDRAM
Hard Drive: 320Gb 5400 Rpm
Graphics Card: AMD Mobility Radeon HD 6310 Graphics
When I open my laptop this morning, my computer froze so I shut it down manually. When it restarted this message appears :
Windows could not start because the following file is missing or corrupt:
windowsystem32c_437.nls
you can attempt to repair this file by starting windows set up using original set up CD-ROM. Select 'r' at the first screen to start repair.
I tried repairing it few times by using the disk but the message still shown up. A site tells me to run chkdsk on start menu, but I could not possibly do that because I cannot reach my desktop. Is there any other way to fix it? What are the EXPAND command? A site is explaining about typing it to a command prompt, but I don't know the step by step procedure on how to reach it. Anyone got any advice on this matter? Please help.
