Same proglem. I was developing on my mac but it kept freezing with continious sandbox
security errors. Then I tried running your demo on the mac and it also freezes.
Noticed that the loaded as2 swf has SecurityError: Error #2000: No active security
context.

Here's more info. Running outside of eclipse seems to work both locally as well as
posted to my server.

Running inside of eclipse on the mac produces continious security errors:

*** Security Sandbox Violation ***
SecurityDomain
'http://www.youtube.com/swf/cl.swf?eurl=&sk=UYQUAE04-iLZqJP54zwgtRzCueGtIBb2C' tried
to access incompatible context 'file:///Users/rainhut/Documents/Flex Builder
3/tubloctest/bin-debug/MainChromeless.html'

Not using Ant to compile.

Yes, the problem seems to be connected to the "debug" process...if you jst RUN your
app inside of eclipse/flex builder, you'll have no problem with it.

...even though, debugging an application without debug it's an hugly process: if you
find a solution to this pls let me know... :) 

I have the same problem. As soon as the debugger connects (console debugger or flex
builder/eclipse) the security exceptions are generated. Afterwards the flex debugger
fails to connect to any other as3/air app, and the browser hangs as soon as it
displays a flash object (tested with safari & firefox). Restarting the browser(s) &
eclipse doesn't help and I also couldn't locate any zombie process. Only rebooting
seems to help.

guys, when i get stuck with this implementation, i did my own, you can use it if you
want. not well documented, but works
http://yikulju.com/blog/?p=197

Hey guys,

I've run into the same issue many times.  Here is what I've observed:

This issue occurs when trying to load any swf that uses a localconnection.

It only occurs in FP 10 when attempting to debug.  Switching back to the debug
version of FP 9 will "fix" the issue (you still have to restart your computer).

You can produce pretty much the same issue by trying to create a localconnection in
an app in the Flash CS4 IDE (when you try to launch the app in the stand alone Flash
Player it will throw security errors and then hang).

I also cannot find any zombie processes.  My best guess is that the Flash Player is
creating a lock on a file or a section of memory that it is not releasing.