As far as I know, freezing is limited to Macs.  In msg220751, Ned said "Further, then pressing "Return", "a", and "Tab" to try a new code completion results in the code completion window momentarily appearing then disappearing." The disappearance , and hence the later reappearance Ned describes, does not happen for me on Windows.

In my view, AutoComplete.py and AutoCompleteWindow.py need to be combined, refactored, re-written, and tested on all systems with a much more complete test suite.