Plug the ORB provided USB stick into a USB port on the 105. Then, in Setup > Device Setup > Persistent Storage, select to use the ORB stick for Persistent Storage instead of the Internal Flash.
Then power cycle the player for this settings change to take effect. (You may need to do an Energy Efficient power cycle rather than Quick Start -- this is a hardware change I've not tested to make sure Quick Start picks it up properly.)
ORB BR should now find the attached USB stick and use it. The 105 will also use that stick for other Persistent Storage needs of various Blu-ray discs, but the two uses won't get in each other's way.
I tried that last night to no avail. But since I assume that you must be right, I tried the rear USB port 1 today (had used the front yesterday) , and viola! Not sure if it is an issue with the front USB drive, but whatever. Thank you again.
By the way, I'm not sure why this little low cost ORB BR isn't discussed more; it has a great interface. I can control it from my phone, and there is much more flexibility in choosing material from my library. Of course, I'm not sure that it plays at the same resolutions as the Oppo Network option....