You need to use the specific version of Python that came with the 1.7.2 SDK. You’ll find it inside c:\Panda3D-1.7.2. You can also try running “ppython” which is a shortcut to this particular version of Python.
For people who are experiencing this issue, check your PYTHONHOME and PYTHONPATH environment variables. You can do this by running ‘env’ from the command line (this should work for Windows, Linux and OSX). If the value of these do not match where you installed Panda3D, you need to use your system’s method of setting environment variables (‘set’ and ‘export’ are likely candidates, google 'how do i set environment variables in '). I suggest creating a script you run when you first open your command prompt to start working with Panda3D, as this ensures that you do not affect any other software that is running on your system.