Have you deleted the [ ; ] before the line?
Delete the
;
Code:
;#define ProgramFiles "D:\Program Files\Bethesda Softworks\Doom 3 BFG Edition"
to look like this
Code:
#define ProgramFiles "D:\Program Files\Bethesda Softworks\Doom 3 BFG Edition"
Before i posted here i have tested this on 5 different computers with different windows installed ( XP ; 7 and 8 -x86 x64-) with no errors.