The answer is in some cases very simple.
Since the last OS X 10.8.5 update the file "mach_kernel" is visible at root level on your hard disk
Believe it or not, some users trash it ?!
Solution in that event:
Simply copy that file (I suppose from a machine running the same updated version of OS X)
Restart.
Your Microsoft update will work (and other ones as well).
Why do I write this?
My sun and I use identical late 2012 Fusion iMacs. Both of us had run the last OS X 10.8.5 update a few days ago.
He trashed "mach_kernel" distrusting that suddenly appeared file.
The Microsoft Update problem was solved when he copied my file. Simply with a usb-stick. & Restart.
Sincerely.
PS:
I now tried the Microsoft update on a mid 2012 MacBook Pro 15" (Retina, SSD) and on a mid 2010 Mac Book Pro 17" both displaying the "mach_kernel" file after an OS X 10.8.5 update.
No problem at all.
This supports my guess that people tamper with the file "mach_kerel".
Eric DV