Did you ever figure out what is wrong?
I'm having same issues (02' WRX)
Every morning since late last week, when I drive to work about 20min in, my stereo starts to flash on and off and I see my boost guage light pulsing and my cluster flashes on and off for a split second.
I do notice that my ignition makes a buzzing noise if I don't turn the key quick/hard enough when I'm trying to start the car. It has been doing this for over a year, I wonder if this could be the cause since the ignition cuts all accessories when you crank the motor. I wonder if this is somehow grounding out due to wear and tear which might be cause all of my accesories inside the car to flash on and off.
What do you guys think?