Thanks for using JustAnswer
I understand that you are having problem with XP crashing on your desktop
You can try using "Last Known Good Configuration"
and see if the computer starts properly
if Last Known Good Configuration works then you have all your data in tact
Please do the following and let me know how things go
Start your computer.
press the F8 key
keep pressing F8 key
When the Windows Advanced Options menu appears, use the ARROW keys to select Last Known Good Configuration (your most recent settings that worked), and then press ENTER.
now windows xp would try to load with LAST CONFIGURATION that worked properly
most likely you would be able to have OS loaded properly
then you can take a backup of your data
after PC loads properly via Last Known Good Configuration most likely it will work fine after wards also
but you may not want to take chances
so take back up of important stuff
Please try and let me know how things go
All the best