BSP_CFG_HANDLE_UNRECOVERABLE_ERROR(0) tied to time delay routine?

Well, 

I had code working before the Xmas break, but of course after the break it is broken - no pun intended.   I get BSP_CFG_HANDLE_UNRECOVERABLE_ERROR(0); and I have isolated it to this line (which used to work):  R_BSP_SoftwareDelay(100,BSP_DELAY_UNITS_MILLISECONDS);

Can you think of any reason why invoking a delay routine would cause this kind of problem?

Thanks

Jim