Hello Arve, Running python2.6 distribute_setup.py works on a vanilla 64 bit CentOS 5 installation but fails on a default vanilla EC2 AMI Linux . Both Pythons were built with 'make altinstall'. Your note suggests that there was a problem with your Python installation. It appears that I too have an installation problem. I installed with 'make altinstall' but how could that go wrong? The python-2.6.6 regression tests for the EC2 version reveal ... test test_zipfile failed -- multiple errors occurred; run in verbose mode for details test_zipimport skipped -- No module named zlib On EC2, when python2.6 distribute_setup.py is run with a Pdb trace at line 1658 n tarfile.py ... (Pdb) print func(name, "r", fileobj, **kwargs) *** CompressionError: gzip module is not available Yet /usr/local/build/Python-2.6.6/Modules/zlib exists for the EC2 build. Please let me know a work-around. Is there anything I should suggest to AWS? With thanks, ned