Help! Windows XP problem

I have a Dell Dimensions 3000. One day while booting up, all I got was a black screen with command prompt.
I put on my Windows XP CD and now it stalls when it says “Installing Windows” There’s a note at the bottom that says “Set up will complete in 39 minutes” it will slowly countdown to 34 minutes and then reboot. Then this process starts all over again.
Can somebody help me?