Nikon File Naming

[Tiziano]

From day 1 my D90 has created NEF files named like: DSC_1503.NEF.
Now, all of a sudden I'm getting this file naming: _DSC1504.NEF.

I prefer the original one and would rather not have to rename every shot.
Does anyone know why and/or how I can get back to it?
Thanks.

Edit,
Just figured out why it's changed. sRGB color space generates the original (DSC_xxxx.NEF) whereas Adobe color space generates the other one.
Dang! I prefer Adobe color space AND the sRGB file naming.:bash

[DsrtVW]

I know on the D300 you can change file naming in menu of the camera to just about any configuration, but I do not know if the D90 has the option. But it would be in the menu of the camera.

[Tiziano]

I know on the D300 you can change file naming in menu of the camera to just about any configuration, but I do not know if the D90 has the option. But it would be in the menu of the camera.
Merely the obvious right. :bash
Thanks, I'll take a look through the options and the manual. Initially I thought the cam had a meltdown or I somehow over shot the memory card.