"SESSION3_INITIALIZATION_FAILED" error

I had spent two days looking for an answer to the stop 6f BSOD and you nailed it by replacing the one file.  "Windows\System32\smss.exe  <-------- most likely, so replace this one first", this file was listed on the affected machine but was 0K.  Replaced it and back up and running.  Thank You.

If you mean you are getting a STOP error that says something like:

SESSION3_INITIALIZATION_FAILED

*** STOP: 0x0000006F (0xc0000034, 00000000, 00000000, 00000000)

It's not RAM, it has nothing to do with chkdsk.

There is no Windows Boot Manager, no Tools, no Memory Diagnostics option in XP...

So far, these Support Engineer suggestions sound like just bad guesses.

One would have to actually see it and learn how to fix the various SESSSION messages.

The usual culprit is some antivirus software - perhaps Avast!, AVG or Avira that has
deleted or quarantined necessary XP files such as the Windows Session Manager file:

c:\windows\system32\smss.exe

You may be able to boot in Safe Mode somebody said and replace the missing file from there.

I suppose the file could have been really infected and quarantined, but that has never been my experience.

What antivirus software are you running and did you just use it prior to this incident?

If the files have been quarantined or deleted, you can just replace them from the copies that are already on your HDD, but to do so you must boot your system into the Windows XP Recovery Console.

Boot into the Windows Recovery Console using a bootable XP installation CD, or create on a
bootable XP Recovery Console CD.

This is not the same as any recovery disks that might have come a store bought system.  If
you are not sure what kind of bootable CD you have, make a bootable XP Recovery Console CD and  be sure.

There are at least four possibilities (that I know of) for these missing files that result in the
SESSION3 or SESSION5 type message:

Windows\System32\smss.exe  <-------- most likely, so replace this one first
Windows\System32\ntdll.dll
Windows\System32\ntoskrnl.exe
Windows\System32\drivers\ftdisk.sys
Windows\System32\winlogon.exe

After booting into the XP Recovery Console, you should be in the C:\WINDOWS folder.  If you are not in the C:\WINDOWS folder you have some other problem that you need to fix first.

When copying files, you may be replacing existing files with the copies, so respond in the affirmative if asked to overwrite existing files.  If the copy succeeds, you should see a message that the file was copied successfully.

In the Recovery Console, from the C:\WINDOWS prompt, enter the following commands:

cd system32
copy c:\windows\system32\dllcache\smss.exe
Reply in the affirmative to any "are you sure" messages so 1 file(s) is copied
exit (your system will restart)

Depending on your system configuration, you may need to copy the files from another location, so if they are not in the dllcache folder for some reason, enter the commands like this:

cd system32
copy c:\windows\ServicePackFiles\i386\smss.exe
exit (your system will restart)