Grrr. Here's a minimal failing set on Win98SE: $ python ../lib/test/regrtest.py test_strptime test_logging test_time test_strptime test_logging test_time test test_time failed -- Traceback (most recent call last): File "C:\CODE\PYTHON\lib\test\test_time.py", line 49, in test_strptime self.fail('conversion specifier: %r failed.' % format) File "C:\CODE\PYTHON\lib\unittest.py", line 260, in fail raise self.failureException, msg AssertionError: conversion specifier: ' %c' failed. 2 tests OK. 1 test failed: test_time $ Remove either or both of the first two, and test_time passes. Probably related: swap the order of the first two, and test_strptime fails: $ python ../lib/test/regrtest.py test_logging test_strptime test_logging test_strptime test test_strptime failed -- Traceback (most recent call last): File "C:\CODE\PYTHON\lib\test\test_strptime.py", line 96, in test_lang "Setting of lang failed") File "C:\CODE\PYTHON\lib\unittest.py", line 268, in failUnless if not expr: raise self.failureException, msg AssertionError: Setting of lang failed 1 test OK. 1 test failed: test_strptime $ These don't smell like wild stores. What happens on your box? If anyone else sees these failures, and can make time to dig, note that 1200 lines in the logging pkg live in logging/__init__.py (easy to overlook! very unusual). Note too that test_logging.py and _strptime.py both muck with locale.