Hi i own an HP  a400n product specs are :

http://h10025.www1.hp.com/ewfrf/wc/genericDocument?docname=c00057188&cc=us&dlc=en&lc=en&jumpid=reg_R1002_USEN

but i gave it 1gig of ram, and an fx 5500 nvidia vid card, runnning  windows xp, upgraded to sp 3

for future references the blue error screen which i talk about:


"A problem has been detected and windows has been SHUT down to prevent damage to your comp."

UNMOUNTABLE_BOOT_VOLUME

2 more paragraphs saying to check hardware and software
and then says

"'Technical Info
***STOP: 0x000000ED (0x862B9438, 0xC0000006, 0x00000000, 0x000000000)"

alright, so i was playing grand theft auto san andreas.... got bored and quit the game, and left the room for about an hour, thinking it would go to the desktop.
When i went back, i was in a black screen and the only thing i could see was the mouse pointer, i ddi alt ctrl delete and the taskbar didnt show up, tried to TURN off the pc with the swicth u use to turn it on, did  alt f4 and nothing happened. So i have a surge protector or suppressor or whatever it is called.. and i flipped the switch to turn off the POWER and restart the pc.... but when i turned it back on it would go to a screen prompting me to choose my operating system either windows xp or windows recovery system. i choose windows xp and another screen followed prompting me to pick from
safe mnode
safe mode with networking
safe mode with something else
last recent settings that worked
or start windows normally

in start windows normally it would go to the windows screen where it has like a little green loading bar and then show me a blue error screen for like half a second and restart
the same thing happened with last recen settings
in all the safe modes, it shows me a list of i guess sytem files and then just restarts
btw the list that it shows is
multi(0)DISK(0)partition2\windows\system 32\drivers\agp440.sys
^^^thats the last file
and then says
press escape to stop loading stp.sys


ok..so i went back to the operating system promp screen and choose recovery but afterthe white line loads it shows the same blue screen that i had seen before.... btw.. i pressed f8 in the os promt screen and it showed me some choices
all the previouse safe mode options
enable boot logging
enable vga mode
lat knwo config (*didn't WORK)
directoryt services mode (windows domain controllers only)
debugging mode
disable auto restart on system failure
start windows normally reboot
return to os choices menu

i did the disable system restart and when i did everything normally it showed me the blue error screen

btw i looked up 0x000000ed on google and it took me to this page
http://support.microsoft.com/kb/297185
but i can't put anything into the system recovey toolTry putting your recovery cd in from HP and choose restore.  It may give you the option to do a non-destructive restore, it may not. 

Try booting to Safe Mode Command Prompt / type the following at the prompt  c:\   then     sfc /scannow

I've not tried it from here but it's worth a shot.  Make sure you have your cd handy.

Alan <>< 

Run free diagnostic tool from your hard drive manufacturer.