Hello, I'm pretty new to programming in general, and I'm trying to get started with python.
Whenever I open up IDLE, everything seems to work fine.
However, when I go to File>New Window, I just get a blank window and everything freezes up.
If I restart my computer, I can open up one new window, but if I try to close it and open up another one, IDLE freezes again.

Does anyone know what might be wrong?

Idle uses the tkinter GUI, which uses Tcl/Tk. Are Tcl and Tk installed on your mac ?
Also: try to run idle from a command line to get the error message.