Can any one help please. Went to start pc today and it won't boot up. Screen saying "Windows could not start because the following file is missing or corrupt. \WINDOWS\SYSTEM32\CONFIG\SYSTEM\. You can attempt to repair this by starting Windows setup CD and selecting "R" to repair". I can't even boot it into safe mode. I have got into repair from the Windows XP CD but don't know what to type into the command prompt. I have had no problems with PC recently. This has just happened out of the blue.