Updated PC to Window 8.1 and found that PaintTool SAI wouldn't start without UAC kicking in no matter what I changes I make to the NTFS permissions..
Found the solution for it via http://nerdanswer.com/answer.php?q=359258
Create a batch file :
set __COMPAT_LAYER=RUNASINVOKER
start .sai.exe
as a workaround.
