Disable the autofocus beam when using a speedlight (Nikon d90)?

Just got my first dslr about 2 weeks ago and just got me a sb-28 from a friend. Basically this is what's bothering me… I focus the shot, camera beeps letting me know its in focus, than I hit the shutter release and the autofocus light beam TURNS BACK ON before the speedlight flash goes off creating about a 1 second delay… Can anyone tell me how to disable it to where soon as I get in focus and hit the shutter release the speedlight flashes and the camera takes the shot… 5STARS TO THE FIRST PERSON WHO FIXES THIS ANNOYING LITTLE BEAM OF LIGHT ON THE FRONT OF MY CAMERA… I have the nikon d90 with the sb-28 speedlight… BTW I already tried disabling the AF assist illuminator in the menu it only disable the beam while I'm trying to focus but dosnt get rid of it between me hitting the shutter release button and the camera taking the shot

Put the lens on manual focus?

While the old SB-28 was a fine flash when introduced, it is not up to the technology of your fine D90

Look instead for a good used Nikon SB-600 or better.

Much of what you are experiencing is due to trying to use older technology with advanced cameras.

If you look on page 234, the compatible Nikon flash units are listed.

That "annoying little beam of light" is the red eye reduction. Shut it off if you don't want it. See page 71 of your manual.