put this code instead
var _menu:ContextMenu = new ContextMenu();
this.contextMenu = _menu;
Unfortunately, this isn't the same menu I mean. The code you suggested does take some items out of the right-click context menu, but it doesn't hide the menu at the top of the executable, which is what i'm after. If you try the code I gave at the top in a CS4 executable (or another earlier flash version) you'll see that you can completely get rid of the menu across the top of the application. That facility has now gone, or so it seems anyway.
Stage.showMenu = false;
showMenu isn't a property of the Stage class, at least not in AS3, so that doesn't work. Unless I'm wrong - have you managed to get an executable to work from Flash CS5 without a menu across the top?
Yep, that's someone else struggling with the same issue. Doesn't really help us solve it though.
I guess it's a "bug" then and unfixable, if you know different, do let me know how to fix it without resorting to external stuff, or using air.
You can't get rid of the RH menus because [I believe] Adobe deemed it necessary to have the Flash version as well as security options and global settings in there for users at all times. At best you can minimize the listings on the right-click menu:
var rightClickMenu:ContextMenu = new ContextMenu();
You can also get rid of the top menu using Resource Hacker, but the right-click menu stays, even if you delete the resource from the .exe file.