This patching thing is enough to drive you over the edge.

I've got an 11.3 system that must support Windows 8.1. I couldn't get
the Window 8.1 Update to install. It threw the "Zen Server or Zen
Loader service is running" error.

This system is not yet production, but soon will be. No workstations
to worry about. They are replacing their XP with Windows 8.1.

I opened an SR. Tech says I don't need the Windows 8.1 Update patch (2
Gigs). I only need the 841566 base patch (400K). I install the 841566
patch and it goes OK. I have a hard time believing that a 2 Gig patch
is replaced in full functionality by a 400K patch.

Can anyone confirm that a base 11.3 install with the 841566 patch will
support Windows 8.1 clients?

I'm thinking it won't. I suspect I need to apply the new patch (also 2 Gigs).

Help me please! Before I go insane!