ActionScript Error #2148:
SecurityError: Error #2148: SWF file file:///C:/Documents and Settings/UserProfile/Desktop/flexstore/bin-release/flexstore.swf cannot access local resource myFile.swf. Only local-with-filesystem and trusted local SWF files may access local resources.


This runtime error is thrown in Flex 3 if some where in the application you are trying to do a httpservice and use a resource from the local folder.
<mx:HTTPService id="fillTreeByCatRPC" url="categories.xml" resultFormat="e4x" />

I have seen this error only in Flex 3, Flex 2 never gave this error.

I did some google and found some solutions. Almost all the solutions suggests that one should change the flex compiler settings.

"add these arguments to the compiler (via Properties - Flex Compiler) : -use-network=false " http://curtismorley.com/2007/08/31/flash-cs3-flex-2-as3-error-2148/#comment-3714

The problem with this solution is that once the settings are changed then the application will not be able to read any remote resource. so the below request will fail
<mx:HTTPService id="fillTreeByCatRPC" url="http://www.resources.com/categories.xml" resultFormat="e4x" />

After doing further searches on Internet, I found that it is the setting problems of the flash player that cause the problem. Basically one needs to set the security settings of the flash player so that it allows the swf file to access the resources on the local system. This is done by visiting the following page
http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager04.html

Make sure that the Global security settings are set to Always Allow

The following screenshot is what we are looking for

Once the settings has been done, Restart the browser and Flex 3 IDE

In all probability the error is gone.