Forum Post: RE: Disabling individual global interrupt on CC2538 causes to entire interrupt enable register reset.

I just found that ALL Interrupt flags have to be cleared writing bit to register:
So the problem was in #2 step:
#2. Disable Interrupt on Bit_0:  INTERRUPT_DISABLE_REG |= 0x00000001;

It has to be:
INTERRUPT_DISABLE_REG = 0x00000001;