>It works if you have flash turned off, its only when flash is >enabled it fires once. > >The flash does work in the interval timer mode. >
I didn't even know that the self timer had that option, but admittedly I never have used the self timer.
Just tried it myself and you are correct that when the built in flash is deployed it only takes one shot. But I just mounted my SB-800 and it does work as expected, so it appears Nikon doesn't feel the built in is powerful enough for it to work as expected and disables multiple shooting with the self timer.
Learn something new every day!!
Edited to add:
When I tested it with the SB800 I was relatively close with a wide aperture and the flash fired every time. But I just retested insuring the flash needed to fire near full power and I only got two flashes for three exposures set, so it appears while the self timer interval works, there's no guarantee that there will be enough flash power.