Make sure the camera shield is getting 5V power. If you are using a uartsbee to program it make sure the switch is in the 5V position. Also try resetting the camera using the reset button on the camera shield followed by resetting the arduino under it. If it gets interrupted while taking a picture or moving data to SD card it will hang the next time you upload your sketch and run it.
I have found the camera shield works well on a Stalker V2.3 without XBee radio installed. I’m using software serial on pins 4,5 with corresponding jumpers on the camera shield to communicate with the camera shield. You need to put this pin configuration in the arduino sketch. I’m using pin 2 for radio communication which is why I moved the port. This is probably not an issue for you.