Error 2142 - security sandbox violation

Hi,

I have a problem when I try to compile my player, I get the following error:

SecurityError: Error #2142: Security sandbox violation: local SWF files cannot use the LoaderContext.securityDomain property. file:///C|/development/Flash/Pathe%20ads/New%20cmpt%20sample%20code/AS3ComponentDemoCode%5Fv2.1/DemoPlayer3Component.swf was attempting to load http://objects.tremormedia.com/embed/swf/acudeo.swf?rand=949275459.

What's odd is that:

1. I have used Security.allowDomain("http://objects.tremormedia.com/"); in the source code

2. This was working fine the day before last!

I have tried adding a crossdomain.xml file in the folder where I build the player, still no joy.

Can anyone help me with this? I tried throughout yesterday to fix it to no avail. I've even tried installing and building the player on a different machine to double check there wasn't something wrong on my PC.

Any help would be great - I'm tearing my hair out!