bernard,
Are you running any anti-virus software, if so, which one? It looks like a case in which scanning could have taken too long, resulting in our extraction not being renamed in time.
Could you shut down Eclipse, and delete the ~/.codemix/engine
folder and restart Eclipse, which will force the re-extraction of the engine? If this does not work, shut down Eclipse again, and rename the freshly extracted engine-extract????
folder to engine
and then start Eclipse.
Do let us know if this works for you.