Hi, this thread may have been resolved, but i recently have had this problem of firestorm logging me out after a minute. Only since moving house - the only change was i was using a different optus supplied modem with my old connection. I was originally using a motorala 4200 with no problem but for my new connection i was supplied a sagecom optus branded on.
I replaced it with my own lynksys adsl modem and the problem went away instantly.
hope that helps!!
mrf.