EDITAR: Por sugerencia de J. F. Sebastian, puedo obtener el mismo error mucho más simple:

Python 2.6.4 (r264:75708, Oct 26 2009, 08:23:19) [MSC v.1500 32 bit (Intel)]
Type "copyright", "credits" or "license" for more information.

IPython 0.10 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object'. ?object also works, ?? prints more.

  Welcome to pylab, a matplotlib-based Python environment.
  For more information, type 'help(pylab)'.

In [1]: open(r'c:\test.bin', 'wb').write('a'*67076095)

In [2]: open(r'c:\test.bin', 'wb').write('a'*67076096)

In [3]: open(r'z:\test.bin', 'wb').write('a'*67076095)

In [4]: open(r'z:\test.bin', 'wb').write('a'*67076096)
---------------------------------------------------------------------------
IOError                                   Traceback (most recent call last)

C:\Documents and Settings\User\<ipython console> in <module>()

IOError: [Errno 22] Invalid argument

In [5]:

Tenga en cuenta que C: es una unidad local y Z: es una unidad de red.

PREGUNTA ORIGINAL:

Python 2.6.4 en Windows XP se bloquea si uso cPickle para escribir un archivo de más de ~ 67 MB en nuestra unidad de red (edición ReadyNAS Pro Pioneer). Me gustaría poder encurtir archivos grandes. ¿Es este un problema conocido? ¿Hay alguna solución?

El siguiente script produce un bloqueo:

import cPickle, numpy

a = numpy.zeros(8385007)
print "Writing %i bytes..."%(a.nbytes)
cPickle.dump(a, open('test_a.pkl', 'wb'), protocol=2)
print "Successfully written."

b = numpy.zeros(8385008)
print "Writing %i bytes..."%(b.nbytes)
cPickle.dump(b, open('test_b.pkl', 'wb'), protocol=2) ##Crashes on a network drive
print "Successfully written." ##Doesn't crash on a non-network drive

Estos son los pasos que tomo para producir un bloqueo en el indicador de ipython:

Python 2.6.4 (r264:75708, Oct 26 2009, 08:23:19) [MSC v.1500 32 bit (Intel)]
Type "copyright", "credits" or "license" for more information.

IPython 0.10 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object'. ?object also works, ?? prints more.

  Welcome to pylab, a matplotlib-based Python environment.
  For more information, type 'help(pylab)'.

In [1]: pwd
Out[1]: 'C:\\Documents and Settings\\User'

In [2]: run test
Writing 67080056 bytes...
Successfully written.
Writing 67080064 bytes...
Successfully written.

In [3]: cd Z:
Z:\

In [4]: pwd
Out[4]: 'Z:\\'

In [5]: run 'C:\\Documents and Settings\\User\\test'
Writing 67080056 bytes...
Successfully written.
Writing 67080064 bytes...
---------------------------------------------------------------------------
IOError                                   Traceback (most recent call last)

C:\Documents and Settings\User\test.py in <module>()
      8 b = numpy.zeros(8385008)
      9 print "Writing %i bytes..."%(b.nbytes)
---> 10 cPickle.dump(b, open('test_b.pkl', 'wb'), protocol=2)
     11 print "Successfully written."
     12

IOError: [Errno 22] Invalid argument
WARNING: Failure executing file: <C:\\Documents and Settings\\User\\test.py>

In [6]:

C: es el disco duro local en la máquina. Z: es nuestro almacenamiento conectado a la red.