A passionate programmer’s findings in the world of internet.

Troubleshooting Window XP c000021a Error (Blue Screen)

Sunday, July 6th, 2008

I found some problems with the built-in bluetooth device in my HP laptop. So, I reinstalled the driver. I reboot the machine after installation completed. When the computer boot up, it failed to enter Windows. It only managed to reach the Windows XP boot up screen, then it restart again itself.

After a few rounds of self reboot, I think I could put it into safe mode then use system restore to restore the system back to the time before I install the new driver.

To put a Windows XP machine into safe mode, all you have to do is to keep pressing F8 button when the computer boots up. Then you will be displayed with an "Windows Advanced Options Menu", which you need to select "Safe Mode".

Unfortunately, safe mode didn't work for me. It has the same fate as before. It reboots before it can enter Windows. The next option I tried was Last Known Good Configuration, but still no luck.

Then, I tried Disable automatic restart on system failure in the "Windows Advanced Options Menu", initiated with the same F8 way.

The Windows XP loading screen showed up. Then, I get a blue screen with the following error:

STOP: c000021a {Fatal System Error}
The Windows Logon Process system process terminated unexpectedly with a status of 0xc0000139 (0x00000000 0x00000000).
The system has been shut down.

Now, I got the error code. I start another computer to search for a solution and I found a Microsoft Knowledge Base article titled How to troubleshoot a "STOP 0xC000021A" error. I thought I found the solution, but it asked me to use a command prompt to enable Dr. Watson. Is the guide silly or I'm the one stupid? How do I do it when I can't start anything, even safe mode in command prompt failed.

Another search result points me to this thread: Blue screen after installation on Win XP. The user mentioned:

Turned out that the problem was caused by the installer overwriting msvcrt.dll in System32, causing the crash.

So, my next attempt will try to replace the file using Recovery Console. Copy the file from another computer and put it into a USB drive. Plug it into the failed computer.

Then, start Recovery Console to copy the file.

  1. Put the Windows XP setup CD into the failed machine.
  2. Start/Reboot the computer.
  3. Press any key to boot from CD.
  4. You will get yourself into Windows Setup.
  5. When the "Welcome to Setup" screen appears, press R to start the Recovery Console.
  6. Press number to select the correct Windows XP installation, then enter the administrator password.

Now, I'm in the recovery console. These are what I did:

  1. Check the date and size of the msvcrt.dll. For my case, it is different from what I can find in another computer. The correct size is at around 335KB.
  2. Backup the original DLL in C:\windows\system32.
  3. Copy the file in USB drive to c:\windows\system32\msvcrt.DLL (Note: you may need to try a few drive letters to find your USB drive.)
  4. Enter "exit" to reboot the computer.
  5. Remove the Windows XP CD and USB drive.

And... my HP laptop is working!

Recover Deleted Files from USB Drive

Saturday, April 12th, 2008

I accidentally deleted a PHP source file with hundreds lines of source code and I'll have to show the system to my client tomorrow. I know I should backup additional copies, but I always think that "I'll do it later".

I found 2 "undelete" tools which I tried to recover the delete file from my USB drive.

Free Undelete 2.0 (Not working)

The Free Undelete from Office Recovery showed up as the first result in Google. Believing in Google's PageRank, I gave it a try.

After installing it, I start it up. The user interface was very user-friendly. Besides that, the file size is only 1MB.

However, as soon as I click on the scan button, the whole program took about 5 minutes to scan. Before it shows any result, Windows XP Error Reporting box showed up, then followed by messages related to Dr Watson. I had to restart my computer to gain control of everything (even 'End task' in the Task Manager does not work).

I'm not sure why it doesn't work for me, or probably it doesn't work on USB drives?

PC Inspector File Recovery (Recommended)

PC Inspector File Recovery was the next program I found.

Very much different from FreeUndelete, the file size was so much bigger, with more than 5MB and the user interface was awful. It takes a while to understand the buttons.

The good part is, it shows all the result instantly and I can find the file that I needed in no time. It also shows the modified date and condition of the files.

Give it a try when you are having the same fate some day.

One important note: If possible, do not perform any activity on the drive you would like to recover. Activities may include copying and creating files. That means, installing the recovery program itself can pose some risks that your deleted file could be overwritten. You may want to install it now, if you think you might need it some day.