Windows 8.1 OSD loses font, deleting FNTCache.dat helps, but why?

Hi Guys

I have to deploy Windows 8.1 to multiple machines with Office 2013 defaulting to a particular font. (Gill Sans)

However after deployment the font disappears, I used DISM in order to place the font files into the WIM Image and deploy again, however that still did not work...

I then did a bit more research into this and come across deleting FNTCache.dat from the System32 folder and restarting.

This did the trick and for all non-opened Office 2013 apps the default font worked.

How can I make sure the font stays without having to delete FNTCache.dat on every machine. I need this to work every time I run an OSD.

Thanks in advance.
NN