I have a HP Pavilion s7520n PC, it loses video after booting

HPhas provided a patch that prevents this issue from occurring. If yourcomputer has this error, you must first use the steps in this documentto resolve the issue before applying the patch. After the problem isresolved you can install sp37394 - Microsoft Windows XP SP3 Upgrade Utility for systems with AMD processors. Doing so, prevents the issue from occurring again and allows Service Pack 3 to be downloaded using Windows Updates.
Microsoft support article: Youreceive a “Stop 0x0000007E” error message after you upgrade to WindowsXP Service Pack 2 or Service Pack 3 on a non-Intel-processor-basedcomputer (In English)

Also it is applicable for all who are using AMD Processor. The remedy as suggested by Hp is:
Prevent the Intel Power Management driver from loading during system startup:

1. Restart the computer in Safe Mode:
   1. Turn off the computer by pressing and holding the power button until the computer shuts down.
   2. Wait about 5 seconds.
   3. Press the power button to turn on the computer.
   4. Turnon the computer and immediately begin pressing the F8 key repeatedly(at the HP or Compaq logo screen) until the Windows Advanced OptionsMenu appears.
   5. Press the Up Arrow key until Safe Mode (top of list) is highlighted, and press the Enter key.
   6. Press Enter again if an OS selection screen displays.The Computer restarts into Safe Mode. If the computer does not restart to Safe Mode and continues to display the Stop error, skip to the next section: Step 2.
2. Click Yes in the “Windows is running in safe mode” window.
3. Right-click the Start button, and select Explore.
4. Browse to C:WindowsSystem32Drivers.
5. Find and right-click the file intelppm.sys.
6. Select Rename and type the text: XXXintelppm.syx.
7. Press Enter and look to make sure the file was renamed successfully.
8. Close the Explorer window, and restart Windows.The error no longer opens and the computer starts normally.
   NOTE: If desired, you can delete the renamed file "XXXintelppm.syx".

Step 2: Use Microsoft Recovery Console to rename intelppm.sys If the computer is unable to open Windows XP Safe Mode, use Microsoft Windows Recovery Console:

1. Restart your computer in the Microsoft Windows Recovery Console.
   1. Turn off the computer by pressing and holding the power button until the computer shuts down.
   2. Wait about 5 seconds.
   3. Press the power button to turn on the computer.
   4. Turnon the computer and immediately begin pressing the F8 key repeatedly(at the HP or Compaq logo screen) until the Windows Advanced OptionsMenu appears.
   5. Press the Down Arrow key until Return to OS Choices Menu (bottom of list) is highlighted, and press the Enter key.
   6. Press the Down Arrow key until Microsoft Windows Recovery Console is highlighted, and press the Enter key.
   7. At the screen “Which Windows installation would you like to log onto” type the number that matches C:Windows, and press the Enter key.
   8. When prompted, type the Administrator password and press the Enter key. If no password has been created, leave the password filed empty, and press the Enter key. The Microsoft Windows Recovery Console opens and a command prompt is shown.
2. At the C:WINDOWS> prompt, type the following: cd c:windowssystem32drivers
3. Make sure the text has been entered correctly and press the Enter key.
4. At the C:WINDOWSSYSTEM32DRIVERS> prompt, type the following: rename intelppm.sys XXXintelppm.syx
5. Make sure the text has been entered correctly and press the Enter key.
6. The computer restarts. If prompted, select Start Windows Normally and press the Enter key.The error no longer opens and the computer starts normally.
   NOTE: If desired, you can delete the renamed file "XXXintelppm.syx"

I hope this helps else visit this site:
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01457284&lc=en&dlc=en&cc=us&lang=en&product=3199127.........sodeep

does any screen appear while in the booting process.