emWin and RTK - Calling GUI_Init() causes Hardfault

Hello,
I am trying to get emWin working in a multi-task system.
I have successfully configured emWin to work in a single task (non RTK) environment.

I have a single video buffer (no FRAME interrupts), the Video buffer is in external SDRAM.
emWin is setup for Linear direct to vram mode.

I have a task for UserInterface (containts GUI_Init() etc...)
I have a 2nd task for a simple timer.
This is a very simple system!

Program boots, I setup clock and I/O pins - all ok.
Then I start a new task to spawn the two above tasks - all ok.

The UserInterface task runs but when it reaches GUI_Init() I get a HardFault.
I can't step into or reach any breakpoint in GUI_X_Config()...

My project is setup as in the "C:\Keil\ARM\Boards\Keil\MCB1700\emWin\Template_RTX" example.

Any ideas??