I had similar problems with my Sony Vaio. If you can't access safe mode (press the F8 key before the boot process, after the PC POSTs), you'll need to use the recovery console to uninstall SP3. You can access the recovery console with a XP installation CD.
Follow the steps below. Yes, it's copied and pasted.
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To remove SP3 from recovery console.
Insert the Windows XP CD in the CD drive or in the DVD drive, and then restart your computer. When you receive the following message, press a key to start your computer from the Windows XP CD:
Press any key to boot from CD
Note The computer must be configured to start from the CD drive or from the DVD drive.
2. When you receive the Welcome to Setup message, press R to start the Recovery Console.
Note: Multiple options will appear on the screen.
3. Select the correct Windows XP installation.
Note: You must select a number before you press ENTER, or the computer will restart. Typically, only the 1: C:\Windows selection is available.
4. If you are prompted to type an administrator password, do so. If you do not know the administrator password, press ENTER. (Typically, the password is blank.)
5. At the command prompt, type
Code:
cd $ntservicepackuninstall$\spuninst
and then press ENTER.
6. At the command prompt, type
, and then press ENTER.
Note The Spuninstal.txt file appears. As the file scrolls down, you will see errors and the files that are being copied. This is typical behavior.
7. After Windows XP SP3 is removed, type exit , and then press ENTER.
8. Restart the computer in safe mode. To do this, press F8 when the computer restarts.
Note After you restart the computer, the computer may stop responding, and you may see a black screen. The mouse will work. In this case, restart the computer again by turning the computer off and then back on. The second restart will let you log on.
When the computer restarts, Windows Explorer (Explorer.exe) does not run, and the Windows icons and the Start button are unavailable. To resolve this problem, follow these steps: a. Press CTRL+ALT+DEL, and then click Task Manager in the Windows Security screen.
b. Click File, and then click New Task (Run).
c. In the Open box, type regedit , and then click OK.
d. Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\RpcSs
e. In the details pane, right-click ObjectName, click Modify, type LocalSystem in the Value data box, and then click OK.
f. Restart the computer
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This is exactly what I did, and it worked perfectly.
