I am using PORT B to supply power to the LCD and generate a tone.
In the code below, when the SOUND command executes, the LCD goes blank.
If I comment out the SOUND command, the LCD stays on. What's going on?

TRISC = %00000000
TRISA = %101100
TRISB = %10000000

@ DEVICE pic16f689,wdt_off

HIGH PORTB.4 'Turn on power to LCD

Define LCD_DREG PORTC 'Set LCD data port
DEFINE LCD_DBIT 0 'Set LCD starting data bit
DEFINE LCD_RSREG PORTC 'Set LCD register select port
DEFINE LCD_RSBIT 4 'Set LCD register select bit
DEFINE LCD_EREG PORTC 'Set LCD enable port
DEFINE LCD_EBIT 5 'Set LCD enable bit
DEFINE LCD_BITS 4 'Set LCD bus size
DEFINE LCD_LINES 2 'Set LCD number of lines

OPTION_REG = %00111000
ANSEL = 0
CM1CON0 = %00000000

LCDOUT $fe,1
LCDOUT DEC 9999

PAUSE 1000

SOUND PORTB.6,[118,200]

END

Thank you for your help.