Version 5512, modification date 14-4-2008, that came with SP3, and version 3156, modification date 13-6-2007, that came with KB398828. The original SP2 one has a modification date of 10-4-2006, which is before I had this PC. So I assume the dates are the dates Microsoft made them, not the date I downloaded them. I'm sure I downloaded SP3 after midnight.
The difference: I've got only one in the Windows folder. It's strange that you have 2. I'd start with renaming the old one to explorer.old and see what happens.
I'm rather sure this isn't related to you shutdown troubles.
I just noticed that my windows xp directory has two explorer.exe files - two different versions, one is names explorer (2). This one appears to be the original version dated 06/13/07 and a version # of 6.00.2900.3156 (xpsp_sp2_gdr.070613-1234).
The newer one is dated 04/13/08 and has a version # of 6.00.2900.5512 (xpsp.080413-2105).
Now, I came across this because I had to kill explorer through task manager earlier this morning because the computer wouldn't shut off, it would just sit there. I figured if I bought up task manager and killed and then restarted explorer I would be able to shut down the computer. This is how I found out I have two explorer files. This is the second time that my computer has acted strangely and not wanted to turn off and I had to hard shut it down with the power button.
I checked the Windows update sight and my update history and there were no windows updates installed on 04/13/08 (the date of the current explorer file).
I am just curious why I have two explorer.exe files and if this is the cause of the computer not wanting to turn off with the Start Turn Off buttons.
I am running Windows XP Media Center 2005 with service pack two. AMD dual core 64+ processor 3800+ with 2 GIG of RAM.
Thanks in advance for your replies.