Why is the debugger hanging?

Hi

I'm writing my first ARM application. I have C++ code that works in Visual Studio on Windows and I am porting it to ARM using ARM Dev Studio. I want to target Cortex M6 but am currently targeting Cortex-A53 as that is suggested in the tutorial.  My code builds ok and runs ok in the debugger up to a certain point, at which the debugger hangs when I try to step over the next line:

It seems to be a consequence of accessing the pointer rather than the cout. Earlier cout's work ok. I think the pointer is valid.

Please can you help me find out why this is happening? I don't know what to do next.

Thanks

David