Nothing executes at prompt. (Ubuntu)

edit

I installed the sagemath software on an Ubuntu machine and nothing executes. I type

sage: notebook()
NameError: name 'notebook' is not defined


sage: 2+3
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/bin/<ipython console> in <module>()

NameError: name 'Integer' is not defined

On opening sage I get the following message. I just installed sage and I have no idea what this means or how to correct it.

----------------------------------------------------------------------
| Sage Version 4.7, Release Date: 2011-05-23                         |
| Type notebook() for the GUI, and license() for information.        |
----------------------------------------------------------------------
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/lib/python2.6/site-packages/IPython/ipmaker.pyc in force_import(modname)
     64         reload(sys.modules[modname])
     65     else:
---> 66         __import__(modname)
     67 
     68 

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/bin/ipy_profile_sage.py in <module>()
      5     preparser(True)
      6 
----> 7     import sage.all_cmdline
      8     sage.all_cmdline._init_cmdline(globals())
      9 

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/lib/python2.6/site-packages/sage/all_cmdline.py in <module>()
     12 try:
     13 
---> 14     from sage.all import *
     15     from sage.calculus.predefined import x
     16     preparser(on=True)

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/lib/python2.6/site-packages/sage/all.py in <module>()
     89 from sage.algebras.all   import *
     90 from sage.modular.all    import *
---> 91 from sage.schemes.all    import *
     92 from sage.graphs.all     import *
     93 from sage.groups.all     import *

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/lib/python2.6/site-packages/sage/schemes/all.py in <module>()
     23 from jacobians.all import *
     24 
---> 25 from hyperelliptic_curves.all import *
     26 
     27 from plane_curves.all import *

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/lib/python2.6/site-packages/sage/schemes/hyperelliptic_curves/all.py in <module>()
----> 1 
      2 
      3 from constructor import HyperellipticCurve
      4 from hyperelliptic_generic import is_HyperellipticCurve
      5 from kummer_surface import KummerSurface
      6 from invariants import (igusa_clebsch_invariants,
      7                         absolute_igusa_invariants_kohel,

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/lib/python2.6/site-packages/sage/schemes/hyperelliptic_curves/constructor.py in <module>()
      9 #*****************************************************************************

     10 
---> 11 from sage.schemes.generic.all import ProjectiveSpace
     12 
     13 from hyperelliptic_generic import HyperellipticCurve_generic

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/lib/python2.6/site-packages/sage/schemes/generic/all.py in <module>()
      2 
      3 from spec             import Spec, is_Spec
----> 4 from affine_space     import AffineSpace, is_AffineSpace
      5 from algebraic_scheme import is_AlgebraicScheme
      6 from ambient_space    import is_AmbientSpace

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/lib/python2.6/site-packages/sage/schemes/generic/affine_space.pyc in <module>()
     22 from sage.misc.all import latex
     23 
---> 24 import algebraic_scheme
     25 
     26 import ambient_space

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/lib/python2.6/site-packages/sage/schemes/generic/algebraic_scheme.pyc in <module>()
    141 import affine_space
    142 import projective_space
--> 143 import toric_variety
    144 import morphism
    145 import scheme

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local/lib/python2.6/site-packages/sage/schemes/generic/toric_variety.py in <module>()
    234 import sys
    235 
--> 236 from sage.geometry.cone import Cone, is_Cone
    237 from sage.geometry.fan import Fan
    238 from sage.matrix.all import matrix

/home/myusername/Downloads/sage-4.7-linux-32bit-ubuntu_10.04_lts-i686-Linux/local ...