I'd suggest that you add a line: print 'Done'; <STDIN>; just before the end of the program. When the prompt appears, pop up he task manager (or better, Process Explorer if you have it), and monitor the memory usage at that point. Then, leaving the manager window visible, hit enter on the command session and watch what happens.

Personally, I've never seen the situation where 'out of memory' occurred during clean up, but that doesn't mean it couldn't happen.

But the thing that is baffling me is why you are still running out of memory now you've reduced the memory usage? Perhaps now would be a good time to post the latest version of your code and see if other people (me) can reproduce your findings.

Remember to include the initial input file--or sufficient information to allow us to accurately mock it up--so that we can run the code in a realistic fashion.