logging module - restricted mode error

[Paul Rudin]

I'm occasionally seeing tracebacks like this:

Traceback (most recent call last):
  File "logging/__init__.py", line 744, in emit
  File "logging/__init__.py", line 630, in format
  File "logging/__init__.py", line 421, in format
RuntimeError: instance.__dict__ not accessible in restricted mode

I'm not sure what it means. Googling leads me to 
<http://docs.python.org/lib/restricted.html> but that says that those
modules were disabled in 2.3 and I'm running 2.5.1. In any case I'm
not using them (although it could be that one of the 3rd party modules
I'm using does something.)

Could someone please explain what this error means?