Default_Handler - HardFault

While working through debugging I keep ending up in the Default_Handler (startup_S7G2.c).  I've traced this down to a HardFault.  When I do a backtrace I get the following:

0x000058a0 in _tx_thread_schedule () at ../synergy/ssp/src/framework/el/tx/tx_src/synergy/tx_thread_schedule.c:145

#3 0x00006396 in _tx_initialize_kernel_enter () at ../synergy/ssp/src/framework/el/tx/tx_src/tx_initialize_kernel_enter.c:179
#4 0x2000d810 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Can you assist?  How can I find the source of the hard fault?

Thanks,

Rich