Interrupt 10 & interrupt 4 clashing?

Hi!

I have the following code:

int fnRIIRQ() interrupt 4
{
LED = !LED;
return;
}

void Dummy5 (void) interrupt 10
{
}

main()
{
while(1);
}


Looking at the code nothing should happen, there is not serial port connected, but initerrupt 4 is triggering (ie. the LED flashes) at a rate of 7.~hz.

If I change interrupt 10 to interrupt 9 then nothing happens as expected.

Q: why is this happening?

Andrew