A similar problem arises with WinXP when trying to configure IDLE via the "Options>Configure IDLE..." menu.

Clicking on the 'Ok' or 'Apply' buttons of the dialog seemingly has no effect. However when closing the window by clicking on either the window close button (top right 'X') or the 'Cancel' button, several bahaviors are observed depending on how many times one has clicked on the 'Ok' and/or 'Cancel' buttons before:
- 0 clicks => expected behavior (dialog is closed, IDLE session is resumed and working fine)
- 1 or 2 clicks => dialog is closed but the IDLE shell behaves as a text editor instead of an interpreter
- 3 or more clicks => IDLE crashes...

Note: I'm running Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit (Intel)] on win32 -> WinXP SP2