This is a discussion on Close... within the Tech Support forums, part of the Knight Online (ko4life.com) category; Close!...
clear register also
Start -> Run -> type regedit -> find knightonline and delete all
HKEY_LOCAL_MACHINE=>SOFTWARE=>KnightOnline (delete the entire folder)
did you delete the ko folders from both HKEY_LOCAL_MACHINE and HKEY_CURRENT_USER and it still wont let you install ?
et a new computer :P
Or try to make a new account on computer that could erase some stuff im not shure