If all your content is installed in the Poser content Runtime, you won't encounter this problem. It's only when you install content in Runtimes that do not have the Geometries/Balance folder.
I only install content to the Poser Runtime that comes with Poser, and I rarely use content that comes with Poser. Everything I purchase, create, or beta test is installed in separate Runtimes depending on the type of content. When I load products from one of those Runtimes, I set that Runtime as the active Runtime.
If I have any library other than the Poser 11 Content (which is the Renderosity Poser Runtime) or the Poser 11 Content Smith Micro (which is the old Smith Micro content Runtime) set as the active Runtime, Poser is not able to find com.obj.
I doubt it matters where you installed the Poser Content Runtime. It's whether a Runtime with the Geometries/Balance folder is the active Runtime.
Loading content from my Poser 11 Content, Poser is able to find com.obj. Now that Poser knows where com.obj is located, I can change my active Runtime to another Runtime, and Poser is still able to find com.obj.
However if I close and relaunch Poser, and change the active Runtime to a Runtime that does not have the Geometries/Balance folder, Poser is not able to find com.obj when I load content from that Runtime.
In this case, I loaded Dawn SE from my Figures Runtime, and Poser could not find com.obj.
Once I locate com.obj, I can change my active Runtime as much as I want, and Poser remembers where com.obj is located (until I close and relaunch Poser.)