SCCM Clients failing to install windows updates

Just a quick one..
I recently pushed a software update via SCCM to around 3000 clients and had around 15 come back as failing. I found that they had a value for a proxy set in the registry at this location:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Connections\WinHttpSettings

Internally the clients shouldnt go via a proxy to grab these updates so I backed up the key and deleted the value WinHttpSettings
and lo and behold the updates now work!.

So now I need to find out where those clients are getting this value from and I also need to do some more testing and implement this fix
Cheers