Camera will not take picture

SOURCE: No picture is taken when shutter release button is pressed

Are those NiMH batteries? Have you tried resetting the camera? If no standard way, just take out batteries for a few minutes, the more the merrier, let the tension build, and replace them. Try tapping on the lens area, it might loose something up. Best I can do, know it aint much ;] Good luck!

SOURCE: nikon d40 autofocus

Dan62, your camera will never be able to focus on objects with no contrast. The manual specifically states this. However, you can put the AF marker over something with some contrast, half press the shutter, so that it will focus, hold the shutter button halfway while you recompose the shot, and then press it all the way.

A note to others using the D40/D40X/D60 that are having problems with autofocus: please remember that this camera will not autofocus with mechanically driven lenses. It will only AF with "AF-S" or "AF-I" lenses.

SOURCE: Shutter won't release

If the lighting is low and shutter speed is set for a long period of time its the function of the camera taking the picture. If it is a malfunction of the shutter take it in for cleaning you might have foriegn material stuck in your shutter mechanism

SOURCE: Nikon D40X stopped auto-focusing yesterday

I had the same problem. My issue was with all my lenses. I solved it by going to the menu and selecting the custom setting menu (pencil icon). Then from the right menu select the AE-L/AF-L and press OK. Then make sure it is set on AE/AF Lock. Presto...all my lenses worked on auto-focus.

SOURCE: R07 Message When Shutter Release Is Held Down Halfway

The r07 is not an error. It's simply telling you how many more shots you could take in burst mode before the buffer fills up.