Access of LPC_CCU1->CLKCCU[CLK_USB1].CFG (0x40051900) crashes RedLink

Discussion created by lpcware Employee on Jun 15, 2016
Content originally posted in LPCWare by chris_bayley_trimble on Thu Dec 18 19:10:41 MST 2014
So further to my 'cannot halt cores' thread I have found the cause is as little as a read access of 0x40051900.

uint32_t*   ptr = &(LPC_CCU1->CLKCCU[CLK_USB1].CFG);
uint32_t    val = *ptr;

Upon stepping through the second line above I loose comms with RedLink. What is going on here ?
I haven't been able to trap any exceptions as comms is already lost.

I want to Disable USB1_CLK so I can enable ULPI.