How far does your boot process go and what is the last message(s) you
see? "Can't restart" is not enough information.
KB307545 describes a method to recover from a possibly corrupted
registry - it is not the equivalent of a System Restore.
If you are seeing the messages in KB307545 (or anything like them),
you should first verify the integrity of your file system. If your
files system is not intact, you probably can't copy the 5 files even
if you wanted to.
If you have access to a bootable XP installation CD, boot the Recovery
Console from the CD and run chkdsk /r.
If you do not have access to a bootable XP installation CD, you may
not be SOL.
Make a bootable CD with RC on it and then run chkdsk /r.
You can make a bootable Recovery Console CD by downloading an ISO file
and burning it to a CD.
The same XP Recovery Console commands can be run from the bootable
Recovery Console CD.
The bootable ISO image file you need to download is called:
xp_rec_con.iso
Download the ISO file from here:
http://www.mediafire.com/?ueyyzfymmig
Use this free and easy program to create your bootable CD:
http://www.imgburn.com/
It would be a good idea to test your bootable CD on the computer that
is working.
You may need to adjust the computer BIOS settings to use the CD ROM
drive as the first boot device instead of the hard disk. These BIOS
adjustments are made before Windows tries to load. If you miss it,
you will have to reboot the system again.
When you boot on the CD, follow the prompts:
Press any key to boot from CD...
The Windows Setup... will proceed.
Press 'R' to enter the Recovery Console.
Select the installation you want to access (usually 1: C:\WINDOWS)
You may be asked to enter the Administrator password (usually empty).
You should be in the C:\SYSTEM folder. This is the same as the C:
\WINDOWS folder you see in explorer.
RC allows basic file commands - copy, rename, replace, delete, cd,
chkdsk, fixboot, fixmbr, etc.
From the command prompt window run the chkdsk command on the drive
where Windows is intalled to try to repair any problems on the
afflicted drive. It is okay to run chkdsk even if it doesn't find any
problems.
Assuming your boot drive is C, run the following command:
chkdsk C: /r
Let chkdsk finish and correct any problems it might find. It may take
a long time to complete or appear to be 'stuck'. Be patient. If the
HDD light is still flashing, it is doing something. Keep an eye on
the percentage amount to be sure it is still making progress.
Remove the CD and type 'exit' to leave the RC and restart the
computer.
You do not have to adjust the BIOS again to boot on the HDD since the
CD will not be present.
Here is additional information about how to start Recovery Console:
http://support.microsoft.com/kb/314058
Here is additional information about the Recovery Console commands you
will be using:
http://support.microsoft.com/kb/314058
You can consider adding RC as a boot option to your system.
A good idea (now that you have had this experience) is to create a
bootable XP installation CD with the latest Service Pack already
installed.