Author: Richard
[Added to the original trac issue at 7.06pm, Tuesday, 21st August 2012]

Just installed 11.3.300.271 on my Mac and it works fine for me (tested in Safari 5.1.6 and Opera 11.5).

You could try installing the Debug Player and seeing if it pops up any exceptions.

Author: warling
[Added to the original trac issue at 6.32am, Thursday, 23rd August 2012]

I've downloaded the latest and greatest version of Flash (11.4.x) along with the Flash Debug Player. The map still doesn't display in this version of Flash on my machine, but the Debug Player does spit out the following error:

Error: Error #2130: Unable to flush SharedObject.
at Error$/throwError()
at flash.net::SharedObject/flush()
at net.systemeD.potlatch2.collections::Stylesheets/setStylesheet()
at net.systemeD.potlatch2.collections::Stylesheets/onStylesheetsLoad()
at MethodInfo-3653()
at net.systemeD.halcyon::FileBank/addFromFile()
at net.systemeD.potlatch2.collections::Stylesheets/init()
at potlatch2/startApp()

Author: Richard
[Added to the original trac issue at 7.33am, Thursday, 23rd August 2012]

Ah. You've probably got local storage disabled in your Flash Player (aka "Flash cookies"). P2 is trying to remember your settings from last time - selected background etc. - and complaining because it can't get at them.

If you open Apple menu -> System Preferences -> Flash Player -> Storage, you should see a three-position radio box. I'm guessing "Block all sites from storing information on this computer" is selected. Change this and retry.

If this fixes it I'll have a look at putting a try... catch block around the various pieces of SharedObject code so that this doesn't cause P2 to bomb out.

Author: warling
[Added to the original trac issue at 1.46pm, Thursday, 23rd August 2012]

Bingo! That was indeed the issue. I changed it to "Ask me before..." and now it works fine with the following exception, which I get twice while loading:

Error #2044: Unhandled NetStatusEvent:. level=error, code=SharedObject.Flush.Failed

(For what it's worth, I'd prefer to leave the setting at "Block all sites..." because, well, you know...paranoia :-)

Thanks for your help! I'll leave you to close out the bug once you've made the necessary changes.

Author: Richard
[Added to the original trac issue at 4.32pm, Saturday, 1st September 2012]

Fix committed in systemed/potlatch2@f5ffc13 . But you should let openstreetmap.org store SharedObjects anyway ;)