ACtheTROLL, thanks for your input.
I may not have been clear earlier, the following may clarify matters.
The initial error msg was "Windows XP could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM "
I found a possible solution on the Microsoft website by referring to this error message, (
http://support.microsoft.com/kb/307545/en-us)
which involves accessing the command prompt.
Unfortunately as the PC won't boot into any mode, even safe mode, I am unable to follow instructions from Microsoft.
In desperation (and have since been advised by IT dept at work) to try using the installation disk to do a repair, which also does not work - this is where the error msg in original post comes from.
I just don't know if there's any way to get into the system, any helpful suggestions?