USB Interrupt Masks not loading STM32L151CC

Question

I'm currently encountering a strange issue with the STM USB libraries. I am able to successfully load firmware onto the STM32L152D-EVAL board (which uses an STM32L152ZD), however, I am unable to modify the same code to work on my form-factor board, which uses the aforementioned STM32L151CC.

After stepping through the code with the debugger (a ULINK2, using the KEIL uVision4 IDE), I noticed that the code would crash while setting the interrupt mask in the function USB_SIL_Init()

uint32_t USB_SIL_Init(void)
{
  /* USB interrupts initialization */
  /* clear pending interrupts */
  _SetISTR(0);
  wInterrupt_Mask = IMR_MSK;
  /* set interrupts mask */
  _SetCNTR(wInterrupt_Mask);
  return 0;
}

More specifically, _SetCNTR(wInterrupt_Mask); is what gives me the error. I haven't changed the value of IMR_MSK between either board. It's value is given as

#define IMR_MSK (CNTR_CTRM | CNTR_WKUPM | CNTR_SUSPM | CNTR_ERRM | CNTR_SOFM \ | CNTR_ESOFM | CNTR_RESETM )

which is 0xBF00

_SetCNTR is defined as follows

 #define _SetCNTR(wRegValue)  (*CNTR   = (uint16_t)wRegValue)

With CNTR being defined as

/* Control register */
#define CNTR    ((__IO unsigned *)(RegBase + 0x40))

And RegBase is

#define RegBase (0x40005C00L)  /* USB_IP Peripheral Registers base address */

I'm currently looking through STM's documentation on this, but I can't seem to find anything specifically relating to the default states for the two different chips. I'm guessing it has something to do with the base address, however the Datasheet shows that this is the correct address.

Can anyone help me out on this?

Thanks!