hello guys. i bought a pod hd500 last week. everything is perfect for me on that unit, except for that:

i have my pod connected to my mac through usb and the output R/L MONO connected to my monitor speakers (the ones that i use on my mac, too). so i use my pod as an audio interface for my mac, too. after some hours of being powered on (the pod hd), the sound i hear from my speakers stops! the pod, however, continues to work... (i can change presets, change the effects etc.) !!! when that happens, i plug out my pod hd, and plug it in again, and everything is fine. however, some of the times that this has happened to me, my mac restarts...!!! and before the restart is finished there is a message something like that: the computer restarted becsuse of a problem! what do you think i should do for that problem?