Joe: Long time no hear. I also recommend from personal experience NOT switching between users while rendering. Better yet, don't have more than one user logged in while rendering. Remember also that around midnight every night, OS X does some HD housecleaning like disk optimization or defragging. Bad time to be competing for CPU and disk access. I'm using a dual G5 and latest Panther. Go not back to P4, that way lies lameness. Considering the amount of postwork P4 made you go through on your comics, it's worth it to get P5 under your fingernails to eliminate some of that. What's new in your end?