Alright, downloaded DS4, removed the CMS, rebooted, loaded DS, closed the My Stuff tab so I wouldn't accidentally click it, set up a quick scene, and rendered without any problems.

However, Preta-3D's Reality plugin has completely spoiled me rotten.  The core DS program is useless to now.  Definitely going to wait until DS4 Advanced is released and the Reality plugin is updated before I even consider upgrading.

Meanwhile, last night I started reading up on how to take better advantage of Poser's Firefly engine to get the kind of detailed renders I like. Not necessarily hyper-real, just... highly detailed. I've been having a lot of fun with the Reality plugin for DS3A, but I'm really tired of trying to get some of my more Poser-specific content to work with it.