Unplanned NIOS2 RESTART !

Here is IRQ handler

And i find what string is influent to unplaned RESTART

I mark in comments my try's and effects wich i get

(1) - I try set IRQ wich can interrupt sound IRQ

Result - NO EFFECT (SOUND WORK but VIDEO crash refresh)

(2) - I try set manual enable VGA_IRQ

Result - NO EFFECT (SOUND WORK but VIDEO crash refresh)

(3) - I try to enable ALL Interupts inside Sound_irq

Result - I get workable Sound and Video - ALL work's fine but sometimes nios restart programm by random way.

void __irq_sound_handler(void* context,alt_u32 id)

{

if((dsp_buff[0] & FIFO_A_EMPTY) && playing)

{

// alt_u32 old_priority=alt_irq_interruptible(VGA_DMA_IRQ); // (1).

// alt_irq_enable_all(NIOS2_STATUS_PIE_MSK); //(3)

// alt_irq_enable(VGA_DMA_IRQ); (2)

FillSndBuff(); // fill sound fifo

counter++; // counter of irq calls

dsp_buff[1]=1; // IRQ ENABLE FLAG

// Enable sound IRQ for next call (by default it IRQ ENABLE cleared when i sound fifo get chipselect)

// IRQ is asserted when FIFO buffer signal almost_empty get rising edge

// alt_irq_non_interruptible(old_priority); //(1).

}

}

So I want create interuptable IRQ handler

What I do wrong ?

Any Ideas ?