My Nikon D40 is having problems focusing?

I have two lens that came with it (I bought it used) I have a 18-55mm and a 55-200mm. The issue is the 18-55mm, whenever it is on automatic it has an issue focusing. It will take forever trying to focus itself and just never takes the shot, so I end up just switching to manual. However, when I use 55-200mm I don't have this problem. Its completely fine! I'm not a wiz with photography, but I'm trying to work on it because I do want to learn as much as I can.

Then someone once told me its because the body is too slow for the lens? So if this is the case then what does that exactly mean?

"Then someone once told me its because the body is too slow for the lens? So if this is the case then what does that exactly mean?" What that means is that the person has NO clue. Nikkor AF-S lenses do NOT need the camera to auto focus the lens. That is in the lens itself.

You need to assure that you follow the instructions in your user manual when using the 18-55 mm lens.

There are may reasons why a lenses "searches" for focus.

* The lighting is too low and you do NOT have the focus assist lamp activated
* The subject you are shooting does not have enough contrast for the focusing system to reference when focusing
* You do not have the focus point covering the subject, but aimed somewhere else like a blank wall

You are probably
1) trying to focus on something too close to the front of the camera
2) trying to focus on something too dark
3) trying to focus on something that the camera can't recognize, such as a white wall
4) or any combination of the three above.

Make sure you wipe any dust off the glass on the lens, make sure nothing is on the metal prongs that connect to the camera.