Missing or Corrupt c:\windows\system32\config\system file

[badatbackups]

I have the following error, but the problem is that I purchased my PC 6 years ago from a retailer fully loaded and I received NO discs with it.  Here's the message:

"Windows could not start because the following file is missing or corrupt: c:\windows\system32\config\system.
You can attempt to repair this file by starting Windows Setup using the original CD-ROM. Select 'r' at the first screen to start repair. 

My PC is an HP multi media center 873n running XP home. 

Any help is greatly appreciated!!!!  Thank you kindly. 

[Broni]

Will it boot into Safe Mode?
If not, you may have RAM problem, Try to re-seat it. If you have more then one stick of RAM, try to start your computer with one RAM module at a time.

[kuszmania9999]

Ram?how can it be?

[Broni]

how can it be?

Google that error.

[badatbackups]

I'm only an intermediate user, so I'm afraid I don't know how to do what your asking.  Is there a reference site or directions on how to do this that you are aware of? 

Thanks very much for your help. 

[Broni]

It looks like your model comes with one 512MB memory stick.
Turn off your computer, open the case. You'll see this:

Touch any bare metal part of your computer (power supply will do), then remove your RAM stick. Clean connectors with eraser. Put it back. Don't close the case. Restart your computer.
If it doesn't work, turn it off, and put your RAM in second slot. Try again.

BTW...your manual is here:
http://h10032.www1.hp.com/ctg/Manual/bph07860.pdf