no prob.

it sounds like the sirius unit is malfunctioning. it could be sending an aberrant signal spike when losing the satellite signal causing the radio to switch and protect itself by skipping the aux mode.

try this:

ipod -> aux adapter and play the ipod. turn the ipod off. if it remains in AUX, i'd switch out your sirius tuner to another one. which one is it, btw? if it falls out of AUX, then something is not quite right with the business radio.....