See SystemFileProtection By setting SFCQuota=0, you have allocated 0 space for the dllcache. Typically, when applying a custom theme without the patched uxtheme.dll, Windows will revert to the classic theme. The fact that this is happening in your case suggests that you are either not using the correct uxtheme.dll or it is not being copied during the installation. I can't speculate as to what the specific problem is. What were the last changes you made to your unattended installation immediately before this problem started?