STOP: c000021a (Fatal System Error)

After doing some windows update I was getting the below error message:

STOP: c000021a (Fatal System Error)
The windows Logon Process system process terminated unexpectedly with a status of 0xc0000135 (0x00000000 0x00000000). The system has been shut down.

I am using a Dell laptop and it came with Windows XP but after that I upgraded it to XP Pro and then have used it for almost 3 years. I have Norton Antivirus installed on my machine and the computer is also kept with all the latest updates. Last year I bought a new hard drive. I have cloned it so that I can use my old data. So, I purchased an XP pro reinstall disk and then accessed the recovery console and then booted from reinstall CD and did a Chkdsk repair and fixboot as well, but I was still getting same fatal error message. Now, I dont know what else to do, so can anyone please help.

I think that if you can do a Repair install then it wont try to overwrite the data that you have.

The STOP 0xC000021A error occurs when either Winlogon.exe or Csrss.exe fails. When the Windows NT kernel detects that either of these processes has stopped, it stops the system and raises the STOP 0xC000021A error. This error may have several causes. To solve this issue, follow the method given here - http://support.microsoft.com/kb/156669

I have read dozens of posts today on several board and I am about to lose it!

My error message is stop: c000021a (fatal system error)
.......0xc000026c..

thoughts?