I had this issue with Win-XP after their last updates. Everytime the PC is rebooted it drops the Motu driver.
I never did find a solution to fix it. The only 2 choices I had were to never turn off the PC or be prepared to load the driver after any reboot. I had a shortcut to the driver on the desktop.
I use and RME interface. The guys at Synthax (USA’s RME tech support/distributor) sent me this link
http://www.rme-audio.de/en_support_techinfo.php?page=content/support/en_support_faq_10entryd
Since it is specifically about Win-XP it may not pertain to your problem or not. I don’t know if Win-8 has rewritten how it handles things. You might search RME’s site or Motu or just google Win-8 issues to see if anything pops up. I know that when I edited the registry I introduced some instability. But shortly after the mother board died, the RME failed, and I ended up on a new Win-7 system (and no dropped driver issues).
If you find anything let us know, I still have an XP system that continues to drop the driver. Oh !!! and by the way, I also loose WDM audio so I cannot hear audio from web browsers until I load the Motu driver. Maybe this has to do with a WDM issue?
Later,
Brain