I couldn't let this one pass... A laptop that would not boot is a real frustration. I had pushed the limits on my 3 year old laptop with 4 G. The memory modules I bought were too hot. The fan was always running at full speed.  I should have noticed. Well, it went on for 2 years and probably did some collateral damage to my H/W. Occasionally I used to get the bluescreen of death. After swapping memory modules, I noticed that one of them was a suspect. I got it out, bend it, threw it on the wall and dumped it in my trash can.

When it had the damaged memory, booting in safe mode would make my system get stuck at Mup.sys. It would not go past it. There are several reasons on why Windows XP could get stuck at Mup.sys.  There are several articles out there, which explains about Mup.sys failures. Here is a good one. In my case, I assumed that my registry was probably corrupted. My Googling showed that it has been a frustrating experience for so many people.

Here comes my savior, the System Resuce CD.  System Rescue CD is a Live CD based on Linux. You can download it here. You should be able to boot your system from CD to make it work.. The instructions fade into eternity, if you type too many commands. You may want remember the following commands.

For mapping your dead C drive from Windows XP : ntfs-3g /dev/sda1 /mnt/windows
In this case- I found my SATA drive was mapped as sda1 under /dev.

For networking :  net-setup eth0. I used dhcp for easy setup.
For starting ssh : /etc/init.d/sshd start - It helps in transferring files to another system. Root users are configured for access in ssh. You can change your root user password, and use the new password for accessing the C drive from the outside world using scp or winscp.

At this point, you should have retrieved all your files. Well do the next steps at your own risk. Your Windows XP may not return to its full form after this. You might be able to get some functionality back. I found this Microsoft site on how to restore a system with corrupted registry.  I  could not follow all of the instructions listed here. But I did the equivalent of the  following MS DOS commands on my System running on Artificial Respiration (System Rescue CD). I was not having a Windows XP restore disk, and hence could not follow all of the instructions listed at the MS site.

md tmp
copy c:\windows\system32\config\system c:\windows\tmp\system.bak
copy c:\windows\system32\config\software c:\windows\tmp\software.bak
copy c:\windows\system32\config\sam c:\windows\tmp\sam.bak
copy c:\windows\system32\config\security c:\windows\tmp\security.bak
copy c:\windows\system32\config\default c:\windows\tmp\default.bak

delete c:\windows\system32\config\system
delete c:\windows\system32\config\software
delete c:\windows\system32\config\sam
delete c:\windows\system32\config\security
delete c:\windows\system32\config\default

copy c:\windows\repair\system c:\windows\system32\config\system
copy c:\windows\repair\software c:\windows\system32\config\software
copy c:\windows\repair\sam c:\windows\system32\config\sam
copy c:\windows\repair\security c:\windows\system32\config\security
copy c:\windows\repair\default c:\windows\system32\config\default

Voila!  I was able to boot. I first booted my system in Safe Mode to see if I was having the same problem with Mup.sys. It got past that point. In my setup, it created an Administrator.<bogus> user. I then rebooted back in normal fashion. For all the hard work and googling and this blog... my recovered OS is not going to stay. I will be replacing it with Solaris 10 x86 5/08.  Solaris does not have Mup.sys.. I am hoping that it was only the Memory that was damaged. About my memory stick. I pushed it under my trash can, below the waster papers and peanut shells, like spend uranium.. I am getting a new laptop. Of course with Windows XP !