I tried changing the font type for my ngage QD.
I have managed to change to Tahoma and was working fine.
Later, I tried to change to Comic MS and then my phone cannot start anymore.
It just shows NOKIA and then shutdown my itself.
My Ngage QD dead after changing fonts
Search the forum for "white screen of death" or "wsod" or "w.s.o.d." and you'll be able to find some help there.