Bizarre error from help()

[Roy Smith]

Can anybody explain this bizarre behavior:

---------------------
Roy-Smiths-Computer:play$ py
Python 2.3.4 (#3, Jun 29 2004, 21:48:03) 
[GCC 3.3 20030304 (Apple Computer, Inc. build 1495)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> help (isinstance)
foos bars bazes
Foo
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/local/lib/python2.3/site.py", line 307, in __call__
    import pydoc
  File "/usr/local/lib/python2.3/pydoc.py", line 49, in ?
    from string import expandtabs, find, join, lower, split, strip, rfind, 
rstrip
ImportError: cannot import name expandtabs
>>> 
---------------------