shutdown error message

after loading directx 9b i get an error message on
shutdown…error could not install service vectors
..press any key to continue.. i press a key then it shuts down. the same message appears if i restart in ms dos mode?
ran scandisk..ok viros check..ok check reg..ok
system file checker..ok..scanreg to previous time
still there?..mirosoft knowledge base..nothing
any help i would be gratefull..thanks