poqexec.exe? Where does it come from? Corrupted in CBS log.

Hi.
Trying to install Win7 SP1.

A file is corrupted (presumably from a previous update). How can I tell which update the file came from?

System Update Readiness Tool - CheckSur.log File Analyzis
doesn't work - registry values are don't correspond at all.

for(ii=0;ii<6;ii++)
{
Ran Update Readiness tool.
Tried to update.
Failed.
}

checked SUR log.

(f) CSI Payload File Corrupt 0x00000000 poqexec.exe amd64_microsoft-windows-servicingstack_31bf3856ad364e35_6.1.7601.17592_none_672ce6c3de2cb17f

What is this file? Which update does it come from? Can I obtain it somehow?
It was previously missing - the one in there is from Windows install media.

thanks

Oh, I tried that.
It says it's already installed.
I can't seem to remove it via the Windows Update frontend.

Any suggestions?

I did both.
Ended up just grabbing the file from a similar box with a working installation.
Cheers