Standard (32/64-bit Universal), WebKit, Flash Plugin, and Leopard

I have an Xcode project that builds a Cocoa desktop browser app.

My browser is referencing the standard WebKit.framework on the system (it doesn't embed its own WebKit.framework).

The "base SDK" for my Xcode project is installed on "Mac OS X 10.5".

The "valid architectures" for my Xcode project is set to "i386 ppc ppc64 ppc7400 ppc970 x86_64".

The "Objective-C Garbage Collection" for my Xcode project is set to "Unsupported".

I am building my project on Snow Leopard with Xcode version 3.2.

When I build a browser with "Architectures" set to "32-bit generic", the browser runs fine on Snow Leopard and Leopard (as a 32-bit process) and displays Flash content correctly.

However, when I create a browser with "Architectures" set to "Standard (32/64-bit Universal)" I have a serious problem for Leopard. In this case, the browser works fine (as a 64-bit process) on Snow Leopard and displays Flash content correctly. However, it works fine on Leopard (as a 64-bit process), except that it does not display Flash content. The Flash plugin never seems to load.

Can someone give me any advice on how to set my browser as "Standard (32/64-bit Universal)" so that WebKit will load the Flash plugin on Mac OS X Leopard 10.5? Or is there a reason why this can't work?

(NOTE: in all cases, I have the latest Flash module installed on the system - 10.0.32.18)