Functions with multiple long params

I've created a little test program that runs fine in the simulator, but causes the hardware (80C390) to reset when a function with multiple long parameters is called. This is with v6.22. Am I missing something obvious? Running in the large memory model in a new project (I.E. all other settings as defaults.)

#include <REG390.H>
#include <absacc.h>

#include <stdio.h> 

void wait (void)  {                   /* wait function */
  int i;
  for (i=0;i<20000;i++)
  {
    ;
  }
}
void Serial0_Initialize(void)
{
  //  init serial interface 38400 baud @ 20MHz
  PCON  |= 0x80;   /* Double serial port 0 baud rate */
  SCON0  = 0x50;   /* Async receiver serial port 0 enable */	         
  TMOD  |= 0x21;   /* Timer 0 16 bits, Timer 1 8 bits with auto reload mode */        
  TH1    = 0xF8;   /* Load MSB of Timer 1 */
  CKCON |= 0x10;   /* Timer 1 clock select divide by 4 of xtal freq */
  TCON   = 0x50;   /* Timer 0 run enable, Timer 1 run enable */           
  TI     = 1;      /* Serial port 0 transmitter interrupt flag set */
}

unsigned char xdata* egdBufferGetInt(int buffer, int width, int height, int depth)
{
  unsigned char xdata *curBuf = 0;

  return curBuf;
}

unsigned char xdata* egdBufferGet(long buffer, long width, long height, long depth)
{
  unsigned char xdata *curBuf = 0;

  return curBuf;
}

long egdDrawInt(unsigned char xdata *buffer, int width, int height)
{
  ;
}

long egdDraw(unsigned char xdata *buffer, long width, long height)
{
  ;
}

void main (void)
{
  unsigned char xdata *b;

  // Initialize serial port 0
  Serial0_Initialize();
  printf("Serial initialized!\n");
  wait();

  printf("Trying BufferGetInt...\n");
  b=egdBufferGetInt(0, 320, 240, 1);
  printf("BufferGetInt success\n");
  wait();

  printf("Trying BufferGet...\n");
  b=egdBufferGet(0, 320, 240, 1);
  printf("BufferGet success\n");
  wait();

  printf("Trying Draw Int...\n");
  egdDrawInt(b, 320, 240);
  printf("Draw Int success\n");
  wait();

  printf("Trying Draw...\n");
  egdDraw(b, 320, 240);
  printf("Draw success\n");
  wait();

  while (1)
  {
    printf("Waiting...\n");
    wait();
  }
}

Serial initialized!
Trying BufferGetInt...
BufferGetInt success
Trying BufferGet...
 erial initialized!
Trying BufferGetInt...
BufferGetInt success
Trying BufferGet...
 erial initialized!
Trying BufferGetInt...
BufferGetInt success
Trying BufferGet...
 erial initialized!
Trying BufferGetInt...
BufferGetInt success
Trying BufferGet...
 erial initialized!