That is encouraging.  This is almost certainly a problem with Tk.  The Cocoa Tcl/Tk 8.5 used by Apple and ActiveState has been known to have issues with composite characters.  There are a couple of IDLE things to ask about first.  Have you made any Custom Key Bindings for IDLE?  Or added any IDLE extensions?  Both of these would show up in your ~/.idlerc directory.

On to Tk-related questions:  Which OS X keyboard layout are you using?  Are you using any Input Methods?  (Both of these options are shown in System Preferences.)  What keystrokes are used for the menu shortcuts that cause the hang?  And, by hang, you mean that menu item changes color indicating that it is selected but IDLE freezes at that point?

If you have the time and feel comfortable doing so, it would be helpful to know if the same problems are displayed using the older Carbon Tcl/Tk 8.4.  You could temporarily move your current 2.7 installation out of the way by doing this in a Terminal shell:

    cd /Library/Frameworks/Python.framework/Versions
    sudo mv 2.7 2.7-SAVED
    cd /Applications
    sudo mv Python\ 2.7 Python\ 2.7-SAVED

and then downloading and installing the 32-bit-only (10.3+) 2.7.2 installer from python.org.  It is not necessary to install an ActiveState Tcl/Tk 8.4 for this.  Note that if you have migrated to OS X 10.7 already, you probably will not want to stay with this version because it is not easy with Xcode 4 to install third-party Python packages that require building C extension modules.  You can restore your previous Python by:

    cd /Library/Frameworks/Python.framework/Versions
    sudo mv 2.7-SAVED 2.7
    cd /Applications
    sudo mv Python\ 2.7-SAVED Python\ 2.7