Is it operator error?

So I just got my Canon 40D the other day and I love it! I'm so excited to start using it. Meanwhile, I have been playing around with it at home but I am having a few problems. I have just had it on the full auto mode just messing around. Of course since I am inside the flash will pop up, but when I push the button to take the picture, the flash will go crazy and it will say busy and it won't always take the picture. Last night, I set it to night scene and went outside and it wouldn't take any pictures at all, but the flash would go crazy. Am I doing something wrong? I can't figure out what is going on. I have read the manual for both the lens and the camera and I can't find an answer. Can someone please help, I am becoming very frustrated!