Since switching from 710 to 810 b2 I'm getting occasional pop-ups saying one or the other of my external USB drives is finished being added. Not sure the exact message, it's fairly quick and if I notice it it's because I'm watching something so I kinda tune out the pop-up. I don't sit in front of the TV enough to get a a great idea of timing, but I'd guess maybe once or twice an hour. Doesn't seem to matter what the box is doing, sitting idle, playing a video, mythtv, hulu... The box has been up for days so it's certainly not the initial discovery/mount.
This is on my core/md hybrid. I don't think it's happening on my dedicated md, but I've hardly used the md lately so I can't be sure.
I think you can change that with the "Alert Filter Level", an option under the OnScreen Orbiter or Hybrid. Just can't remember what you change it to.. maybe 2?
Edit: make that "important". At least if it is the same as this:
http://forum.linuxmce.org/index.php?topic=6705.0